Greg is a beginner bodybuilder. Today the gym coach gave him the training plan. All it had was n integers a1, a2, ..., an. These numbers mean that Greg needs to do exactly n exercises today. Besides, Greg should repeat the i-th in order exercise ai times.Greg now only does three types of exercises: "chest" exercises, "biceps" exercises and "back" exercises. Besides, his training is cyclic, that is, the first exercise he does is a "chest" one, the second one is "biceps", the third one is "back", the fourth one is "chest", the fifth one is "biceps", and so on to the n-th exercise.Now Greg wonders, which muscle will get the most exercise during his training. We know that the exercise Greg repeats the maximum number of times, trains the corresponding muscle the most. Help Greg, determine which muscle will get the most training.

The first line contains integer n (1 ≤ n ≤ 20). The second line contains n integers a1, a2, ..., an (1 ≤ ai ≤ 25) — the number of times Greg repeats the exercises.

Print word "chest" (without the quotes), if the chest gets the most exercise, "biceps" (without the quotes), if the biceps gets the most exercise and print "back" (without the quotes) if the back gets the most exercise. It is guaranteed that the input is such that the answer to the problem is unambiguous.

NoteIn the first sample Greg does 2 chest, 8 biceps and zero back exercises, so the biceps gets the most exercises.In the second sample Greg does 5 chest, 1 biceps and 10 back exercises, so the back gets the most exercises.In the third sample Greg does 18 chest, 12 biceps and 8 back exercises, so the chest gets the most exercise.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Threading.Tasks;

namespace codeforce8
{
    class Program
    {
        static string Type(int [] arr,int n)
        {
            int chest = 0;
            int biceps = 0;
            int back = 0;

            double ff = (double)n / 3;
            /*for (int i = 0; i < 2; i++)
            {
                if (arr.Length % 3 == 0)
                {
                    break;
                }
                else arr.Append(0);
            }*/
                for (int  i = 0;  i < (Math.Ceiling(ff))*3;  i+=3)
                {
                    chest += arr[i];
                    biceps += arr[i + 1];
                    back += arr[i + 2];
                }
            if (chest > back && chest > biceps)
            {
                return "chest";
            }
           else if (biceps > back && chest <biceps)
            {
                return "biceps";
            }
           else if (chest < back && back > biceps)
            {
                return "back";
            }
            return "0";
        }
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] arr = new int[25];
            string str = Console.ReadLine();
            string[] st = str.Split();
            for (int i = 0; i < n; i++)
            {
                arr[i] = int.Parse(st[i]);
            }
            Console.WriteLine(Type(arr,n));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Threading.Tasks;

namespace codeforce8
{
    class Program
    {
        static string Type(int [] arr,int n)
        {
            int chest = 0;
            int biceps = 0;
            int back = 0;

            double ff = (double)n / 3;

                for (int  i = 0;  i < (Math.Ceiling(ff))*3;  i+=3)
                {
                    chest += arr[i];
                    biceps += arr[i + 1];
                    back += arr[i + 2];
                }
            if (chest > back && chest > biceps)
            {
                return "chest";
            }
            else if (biceps > back && chest < biceps)
            {
                return "biceps";
            }
            else return "back";
        }
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] arr = new int[25];
            string str = Console.ReadLine();
            string[] st = str.Split();
            for (int i = 0; i < n; i++)
            {
                arr[i] = int.Parse(st[i]);
            }
            Console.WriteLine(Type(arr,n));
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using System.Threading.Tasks;

namespace codeforce8
{
    class Program
    {
        static string Type(int [] arr,int n)
        {
            int chest = 0;
            int biceps = 0;
            int back = 0;

            double ff = (double)n / 3;

                for (int  i = 0;  i < (Math.Ceiling(ff))*3;  i+=3)
                {
                    chest += arr[i];
                    biceps += arr[i + 1];
                    back += arr[i + 2];
                }
            if (chest > back && chest > biceps)
            {
                return "chest";
            }
           else if (biceps > back && chest <biceps)
            {
                return "biceps";
            }
           else if (chest < back && back > biceps)
            {
                return "back";
            }
            return "0";
        }
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] arr = new int[25];
            string str = Console.ReadLine();
            string[] st = str.Split();
            for (int i = 0; i < n; i++)
            {
                arr[i] = int.Parse(st[i]);
            }
            Console.WriteLine(Type(arr,n));
        }
    }
}

using System;
using System.Linq;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            int count = int.Parse(Console.ReadLine());
            int[] s = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int chest = 0,biceps = 0, back = 0;
            for (int i = 1; i <= count; i++)
            {
                if (i % 3 == 1)
                    chest += s[i - 1];
                if (i % 3 == 2)
                    biceps += s[i - 1];
                if (i % 3 == 0)
                    back += s[i - 1];
            }

            Console.WriteLine(chest > biceps && chest > back ? "chest" : biceps > chest && biceps > back ? "biceps" : "back");

        }
    }
}

using System;
using System.Linq;
class Test{
    static void Main(){
        int n = int.Parse(Console.ReadLine());
        int [] a = new int [3];
        string [] line = Console.ReadLine().Split();
        int j = 0;
        for(int i = 0; i < n; i++){
            if(j == 3){
                j = 0;
            }
            a[j] += int.Parse(line[i]);
            j++;
        }
        switch(Array.IndexOf(a, a.Max())){
            case 0:
                Console.WriteLine("chest"); break;
            case 1:
                Console.WriteLine("biceps"); break;
            case 2:
                Console.WriteLine("back"); break;
            default: break;
        }
    }
}

using System;

public class Exercise
{
    static void Main(string[] agrs)
    {

        var input1 = Console.ReadLine();
        var input2 = Console.ReadLine().Split();

        var n = int.Parse(input1);

        int chest = 0;
        int biceps = 0;
        int back = 0;

        for (int i = 0; i < n; i++)
        {
            if ((i + 1) % 3 == 0)
                back += int.Parse(input2[i]);

            if ((i + 1) % 3 == 1)
                chest += int.Parse(input2[i]);

            if ((i + 1) % 3 == 2)
                biceps += int.Parse(input2[i]);

        }

        int max = chest;
        string result = "chest";

        if (biceps > max)
        {
            max = biceps;
            result = "biceps";
        }

        if (back > max)
        {
            result = "back";
        }

        Console.WriteLine(result);

    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace CodeForces
{
	internal class Template
	{
		private static readonly Scanner cin = new Scanner();

		private static void Main()
		{
			//Console.SetIn(new StreamReader(@"C:\CodeForces\input.txt"));
			new Template().Solve();
		}

		private void Solve()
		{
			var n = cin.NextInt();
			var chest = 0;
			var biceps = 0;
			var back = 0;
			for (var i = 0; i < n; i++)
			{
				var c = cin.NextInt();
				if (i % 3 == 0)
				{
					chest += c;
				}
				if (i % 3 == 1)
				{
					biceps += c;
				}
				if (i % 3 == 2)
				{
					back += c;
				}
			}
			if (chest > biceps && chest > back)
			{
				Console.WriteLine("chest");
			}
			else if (biceps > back)
			{
				Console.WriteLine("biceps");
			}
			else
			{
				Console.WriteLine("back");
			}
		}
	}

	internal class Scanner
	{
		private string[] s = new string[0];
		private int i;
		private readonly char[] cs = new[] { ' ' };

		public string Next()
		{
			if (i < s.Length) return s[i++];
			var line = Console.ReadLine() ?? string.Empty;
			s = line.Split(cs, StringSplitOptions.RemoveEmptyEntries);
			i = 1;
			return s.First();
		}

		public double NextDouble()
		{
			return double.Parse(Next());
		}

		public int NextInt()
		{
			return int.Parse(Next());
		}

		public long NextLong()
		{
			return long.Parse(Next());
		}
	}
}

using System;
using System.Linq;

namespace CSharp
{
    public class _255A
    {
        public static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            var type = Console
                .ReadLine()
                .Split()
                .Select((token, i) => new
                {
                    Count = int.Parse(token),
                    Type = i % 3
                })
                .GroupBy(e => e.Type, e => e.Count)
                .Select(g => new
                {
                    Type = g.Key,
                    Count = g.Sum()
                })
                .OrderByDescending(e => e.Count)
                .First()
                .Type;

            Console.WriteLine(type == 0 ? "chest" : type == 1 ? "biceps" : "back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace test1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string[] strs = Console.ReadLine().Split();
            int[] cnt = { 0, 0, 0 };
            for (int i = 0; i < n; i++)
            {
                cnt[i % 3] += int.Parse(strs[i]);
            }
            if(cnt[0]>cnt[1]&&cnt[0]>cnt[2])
                Console.WriteLine("chest");
            else if(cnt[1]>cnt[2])
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Solution
{
    class Program
    {
        static void Main(string[] args)
        {
            var n = int.Parse(Console.ReadLine());
            var Nums = Console.ReadLine().Split().Select( x => int.Parse(x) ).ToList();
            var group = new string[] {"chest", "biceps", "back"};
            var train = new Dictionary<string, int>
            {
                {group[0], 0}, {group[1], 0}, {group[2], 0}
            };
            for (var i = 0; i < n; i++)
            {
                train[group[i%3]]+=Nums[i];
            }
            var max = train.Values.Max();
            Console.WriteLine(train.FirstOrDefault(x=>x.Value == max).Key);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;

namespace Codeforces
{
    internal static class Program
    {
        private const string TEST = "A1";

        private static void Solve()
        {
            Read();
            var a = ReadIntArray();
            var res = new int[3];
            var resStr = new [] {"chest", "biceps", "back"};
            for (int i = 0; i < a.Count; i++)
            {
                    res[i%3] += a[i];

            }
            WriteLine(resStr[res[0] == res.Max() ? 0 : res[1] == res.Max() ? 1 : 2]);
        }

        private static void Main()
        {
            if (Debugger.IsAttached)
            {
                Console.SetIn(new StreamReader(String.Format(@"..\..\..\..\Tests\{0}.in", TEST)));
            }

            Solve();

            if (Debugger.IsAttached)
            {
                Console.In.Close();
                Console.SetIn(new StreamReader(Console.OpenStandardInput()));
                Console.ReadLine();
            }
        }

        #region Reader

        private static string Read()
        {
            return Console.ReadLine();
        }

        private static void Read(out int n1, out int n2)
        {
            var input = ReadArray();
            n1 = int.Parse(input[0]);
            n2 = int.Parse(input[1]);
        }
        private static void Read(out int n1, out int n2, out int n3)
        {
            var input = ReadArray();
            n1 = int.Parse(input[0]);
            n2 = int.Parse(input[1]);
            n3 = int.Parse(input[2]);
        }
        private static void Read(out int n1, out int n2, out int n3, out int n4)
        {
            var input = ReadArray();
            n1 = int.Parse(input[0]);
            n2 = int.Parse(input[1]);
            n3 = int.Parse(input[2]);
            n4 = int.Parse(input[3]);
        }

        private static void Read<T>(out T a1, out T a2)
        {
            var input = ReadArray();
            a1 = (T)Convert.ChangeType(input[0], typeof(T));
            a2 = (T)Convert.ChangeType(input[1], typeof(T));
        }

        private static void Read<T>(out T a1, out T a2, out T a3)
        {
            var input = ReadArray();
            a1 = (T)Convert.ChangeType(input[0], typeof(T));
            a2 = (T)Convert.ChangeType(input[1], typeof(T));
            a3 = (T)Convert.ChangeType(input[2], typeof(T));
        }

        private static void Read<T>(out T a1, out T a2, out T a3, out T a4)
        {
            var input = ReadArray();
            a1 = (T)Convert.ChangeType(input[0], typeof(T));
            a2 = (T)Convert.ChangeType(input[1], typeof(T));
            a3 = (T)Convert.ChangeType(input[2], typeof(T));
            a4 = (T)Convert.ChangeType(input[3], typeof(T));
        }

        private static int ReadInt()
        {
            return Int32.Parse(Read());
        }

        private static long ReadLong()
        {
            return long.Parse(Read());
        }

        private static double ReadDouble()
        {
            return double.Parse(Read(), CultureInfo.InvariantCulture);
        }

        private static T Read<T>()
        {
            return (T)Convert.ChangeType(Read(), typeof(T));
        }

        private static string[] ReadArray()
        {
            var readLine = Console.ReadLine();
            if (readLine != null)
                return readLine.Split(' ');

            throw new ArgumentException();
        }

        private static List<int> ReadIntArray()
        {
            return ReadArray().Select(Int32.Parse).ToList();
        }

        private static List<long> ReadLongArray()
        {
            return ReadArray().Select(long.Parse).ToList();
        }

        private static List<double> ReadDoubleArray()
        {
            return ReadArray().Select(d => double.Parse(d, CultureInfo.InvariantCulture)).ToList();
        }

        private static List<T> ReadArray<T>()
        {
            return ReadArray().Select(x => (T) Convert.ChangeType(x, typeof (T))).ToList();
        }

        private static void WriteLine(int value)
        {
            Console.WriteLine(value);
        }

        private static void WriteLine(double value)
        {
            Console.WriteLine(value.ToString(CultureInfo.InvariantCulture));
        }

        private static void WriteLine(long value)
        {
            Console.WriteLine(value);
        }

        private static void WriteLine(double value, string stringFormat)
        {
            Console.WriteLine(value.ToString(stringFormat, CultureInfo.InvariantCulture));
        }

        private static void WriteLine<T>(T value)
        {
            Console.WriteLine(value);
        }

        private static void Write(int value)
        {
            Console.Write(value);
        }

        private static void Write(double value)
        {
            Console.Write(value.ToString(CultureInfo.InvariantCulture));
        }

        private static void Write(long value)
        {
            Console.Write(value);
        }

        private static void Write(double value, string stringFormat)
        {
            Console.Write(value.ToString(stringFormat, CultureInfo.InvariantCulture));
        }

        private static void Write<T>(T value)
        {
            Console.Write(value);
        }

        #endregion
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;

namespace Codeforces154
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string[] s = Console.ReadLine().Split(' ');
            int[] a = new int[3];

            int k=0;
            for (int i=0;i<n;i++)
            {
                a[k]+=Convert.ToInt32(s[i]);
                k++;
                if (k==3)
                    k=0;
            }

            if (a[0]>Math.Max(a[1],a[2]))
                Console.WriteLine("chest");
            else if (a[1]>Math.Max(a[0],a[2]))
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace A
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int chest = 0, back = 0, bic = 0;
            string[] s = Console.ReadLine().Split();
            for (int i = 0; i < n; i++)
            {
                if ((i+1)%3==1)
                {
                    chest += int.Parse(s[i]);
                }
                if ((i+1)%3==2)
                {
                    bic += int.Parse(s[i]);
                }
                if ((i + 1) % 3 == 0)
                {
                    back += int.Parse(s[i]);
                }
            }
            if (back>chest&&back>bic)
            {
                Console.WriteLine("back");
            }
            if (chest>back&&chest>bic)
            {
                Console.WriteLine("chest");
            }
            if (bic>chest&&bic>back)
            {
                Console.WriteLine("biceps");
            }
        }
    }
}

using System;
using System.Linq;

namespace olymp
{
  internal class Program
  {
    private static readonly string[] Answers = new[] { "chest", "biceps", "back" };

    private static void Main()
    {
      Console.ReadLine();
      var ex = Console.ReadLine().Split().Select(int.Parse).ToArray();
      var count = new int[3];
      for (int i = 0; i < ex.Length; i++)
        count[i % 3] += ex[i];
      for (int i = 0; i < 3; i++)
        if (count[i] == count.Max())
          Console.Write(Answers[i]);
    }
  }
}

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        int n = Convert.ToInt32(Console.ReadLine());
        int[] arr = Array.ConvertAll(Console.ReadLine().Split(' '), item => Convert.ToInt32(item));
        int chests = 0, biceps = 0, back = 0;
        for(int i=0;i<3;i++)
        {
            for(int j=i;j<arr.Length;j+=3)
            {
                if (i == 0) chests += arr[j];
                else if (i == 1) biceps += arr[j];
                else if (i == 2) back += arr[j];
            }
        }
        if (chests > biceps && chests > back) Console.Write("chest");
        else if (biceps > chests && biceps > back) Console.Write("biceps");
        else Console.Write("back");
    }
}

using System;
using static System.Console;
using System.Windows;
using static System.Math;

namespace ConsoleApp6
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(ReadLine());
            string[] b = ReadLine().Split(' ');
            int[] a = new int[b.Length + 1];
            int back = 0, biceps = 0, chest = 0;
            for (int i = 1; i <= b.Length; i++)
            {
                a[i] = Convert.ToInt32(b[i - 1]);
            }
            for (int i = 1; i <= b.Length; i++)
            {
                if (i % 3 == 0) back += a[i];
                else if (i % 3 == 2) biceps += a[i];
                else if (i % 3 == 1) chest += a[i];
            }
            if (Max(Max(back, biceps), chest) == back) WriteLine("back");
            else if (Max(Max(back, biceps), chest) == biceps) WriteLine("biceps");
            else Write("chest");
        }
    }
}

using System;

namespace CodeForce156B_1
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Int32.Parse(Console.ReadLine());
            string[] st = Console.ReadLine().Split(' ');
            int count = 0;
            int sum1 = 0;
            int sum2 = 0;
            int sum3 = 0;
            for (int i = 0; i < st.Length; i++)
            {
                switch (count)
                {
                    case 0:
                        sum1 += Int32.Parse(st[i]);
                        break;
                    case 1:
                        sum2 += Int32.Parse(st[i]);
                        break;
                    case 2:
                        sum3 += Int32.Parse(st[i]);
                        break;
                    default:
                        sum1 += Int32.Parse(st[i]);
                        count = 0;
                        break;
                }
                count++;
            }
            if (sum1>sum2 && sum1>sum3)
                Console.WriteLine("chest");
            else if (sum2 > sum1 && sum2 > sum3)
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
        }
    }
}

using System;

namespace temp
{
	class Program
	{
		public static void Main (string[] args)
		{
			int n = int.Parse(Console.ReadLine());
			string[] str = Console.ReadLine().Split(new char[]{' '},StringSplitOptions.RemoveEmptyEntries);
			int stk=0;
			int[] a = {0,0,0};
			for(int i=0;i<n;i++)
			{
				a[stk]+=int.Parse(str[i]);
				stk++;
				if(stk>2)
				{
					stk=0;
				}
			}
			if(a[0]>a[1] && a[0]>a[2])
			{
				Console.WriteLine("chest");
				return;
			}
			if(a[1]>a[0] && a[1]>a[2])
			{
				Console.WriteLine("biceps");
				return ;
			}
			Console.WriteLine("back");
			return;
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace TASK_255A
{
    class Program
    {
        static void Main(string[] args)
        {
            int count = int.Parse(Console.ReadLine());
            int[] arr = Console.ReadLine().Split().Select(x => int.Parse(x)).ToArray();
            int[] res = new[] { 0, 0, 0 };
            for (int i = 0; i < count; i++)
                res[i % 3] += arr[i];
            if (res[0] == res.Max())
                Console.WriteLine("chest");
            else if (res[1] == res.Max())
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
            Console.ReadLine();
        }
    }
}

using System;
class a
{
    static void Main()
    {
        Console.ReadLine();
        var a = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        int b, c, d; b = c = d = 0;
        for (int i = 0; i < a.Length; i+=3) b+= a[i];
        for (int i = 1; i < a.Length; i+=3) c+= a[i];
        for (int i = 2; i < a.Length; i+=3) d+= a[i];
        Console.WriteLine(b > c ? b > d ? "chest" : "back" : c > d ? "biceps" : "back");
    }
}

using System;
using System.Collections;
using System.Collections.Generic;

	class MainClass
	{
	public static string  findmax(int chest,int biceps,int back)
	{
		int val = Math.Max (Math.Max (chest, biceps), back);
		if (val == chest)
			return "chest";
		if (val == biceps)
			return "biceps";
		if (val == back)
			return "back";
		else
			return "none";
	}

	public static void Main(string[] args)
	{
		int n = Convert.ToInt32 (Console.ReadLine ());
		string[] values = Console.ReadLine ().Split ();
		int[] val = new int[n];
		int check = 0;
		int chest = 0, back = 0, biceps = 0;
		for (int i = 0; i < n; i++) {
			val [i] = Convert.ToInt32 (values [i]);
			if (check == 0) {
				chest =chest + val [i];
			}
			if (check == 1) {
				biceps = biceps+  val [i];
			}
			if (check == 2) {
				back = back + val [i];
				check++;
			}
			check++;
			if (check > 3)
				check = 0;

		}

		Console.WriteLine (findmax (chest, biceps, back));

	}

}

using System;
using System.Linq;
using System.Collections.Generic;

namespace AlgoTasks
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split().Select(s => int.Parse(s)).ToArray();
            int chest = 0, biceps = 0, back = 0;
            for (int i = 0; i < n; i++)
            {
                if (i % 3 == 0) chest += a[i];
                else if (i % 3 == 1) biceps += a[i];
                else if (i % 3 == 2) back += a[i];
            }

            if (chest > biceps && chest > back)
                Console.WriteLine("chest");
            else if (biceps > chest && biceps > back)
                Console.WriteLine("biceps");
            else if (back > chest && back > biceps)
                Console.WriteLine("back");

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace _158Csharp
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string s = Console.ReadLine();
            string[] p = s.Split(new string[] { " " }, StringSplitOptions.None);
            int[] A = new int[n];
            for (int i = 0; i < n; i++)
            {
                A[i] = Convert.ToInt32(p[i]);
            }
            int chest = 0;
            int biceps = 0;
            int back = 0;
            for (int i = 0; i < n; i++)
            {
                if (i % 3 == 0)
                {
                    chest += A[i];
                }
                else if (i % 3 == 1)
                {
                    biceps += A[i];
                }
                else if (i % 3 == 2)
                {
                    back += A[i];
                }
            }
            if (chest > biceps && chest > back)
                Console.WriteLine("chest");
            if (biceps > chest && biceps > back)
                Console.WriteLine("biceps");
            if (back > chest && back > biceps)
                Console.WriteLine("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
             Console.ReadLine();
            string[] y = Console.ReadLine().Split(' ');
            int[] a = new int[y.Length];
            for (int i = 0; i < a.Length; i++)
            {
                a[i] = int.Parse(y[i]);
            }
            int chest = 0;
            int biceps = 0;
            int back = 0;
            for (int i = 0; i < a.Length; i += 3)
            {
                if (i < a.Length)
                {
                    chest += a[i];
                }
            }
            for (int i = 1; i < a.Length; i += 3)
            {
                if (i < a.Length)
                {
                    biceps += a[i];
                }
            }
            for (int i = 2; i < a.Length; i += 3)
            {
                if (i < a.Length)
                {
                    back += a[i];
                }
            }
            if ((chest > back) && (chest > biceps))
            {
                Console.WriteLine("chest");

            }
            if ((back > biceps) && (back > chest))
            {
                Console.WriteLine("back");

            }
            if ((biceps > back) && (biceps > chest))
            {
                Console.WriteLine("biceps");

            }
                //Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A.Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int chest = 0, biceps = 0, back = 0;
            int[] arr = Console.ReadLine().Split().Select(int.Parse).ToArray();
            if (n > 3)
            {
                for (int i = 0; i < n; i += 3)
                {
                    chest += arr[i];
                }
                for (int i = 1; i < n; i += 3)
                {
                    biceps += arr[i];
                }
                for (int i = 2; i < n; i += 3)
                {
                    back += arr[i];
                }
            }
            else
            {
                if (n == 3)
                {
                    chest = arr[0];
                    biceps = arr[1];
                    back = arr[2];
                }
                if (n == 2)
                {
                    chest = arr[0];
                    biceps = arr[1];
                }
                else if (n == 1) { Console.WriteLine("chest"); return; };
            }
            string[] s = { "chest", "biceps", "back" };
            int[] final = { chest, biceps, back };
            Console.WriteLine(s[Array.IndexOf(final, final.Max())]);
        }
    }
}

using System.Text;
using System.Linq;
using System;
using System.Collections;

class Program
{
    static void Main()
    {
        int s1 = Convert.ToInt32(Console.ReadLine());
        string s2 = Console.ReadLine();
        int[] sum = new int[3];

        string[] povtor = s2.Split(' ');

        for (int i=0; i<=povtor.Length - 1; i++)
        {
            sum[i%3] += Convert.ToInt32(povtor[i]);
        }

        if (sum[0] > sum[1] && sum[0] > sum[2])
        Console.WriteLine("chest");
        if (sum[1] > sum[0] && sum[1] > sum[2])
        Console.WriteLine("biceps");
        if (sum[2] > sum[1] && sum[2] > sum[0])
        Console.WriteLine("back");
    }
}

using System;
using System.Text.RegularExpressions;
using System.Collections.Generic;

namespace temp
{
    class MainClass
    {
        private static Int32[] read_ints(int n) {
            string[] str = Console.ReadLine().Split(new char[]{' '});
            Int32[] ret = new Int32[n];
            for (Int32 i = 0; i < n; i++)
                ret[i] = Convert.ToInt32(str[i]);
            return ret;
        }

        private static Int32 read_int() {
            return Convert.ToInt32(Console.ReadLine());
        }

        private static Int64[] read_longs(int n) {
            string[] str = Console.ReadLine().Split(new char[]{' '});
            Int64[] ret = new Int64[n];
            for (Int64 i = 0; i < n; i++)
                ret[i] = Convert.ToInt64(str[i]);
            return ret;
        }

        private static Int64 read_long() {
            return Convert.ToInt64(Console.ReadLine());
        }

        private static string read_line() {
            return Console.ReadLine();
        }

        public static void Main (string[] args)
        {
            int n = read_int(), chest = 0, biceps = 0, back = 0, m = 0;
            int[] arr = read_ints(n);
            for (int i = 0; i < n; i++) {
                if (m == 0)
                    chest += arr[i];
                else if (m == 1)
                    biceps += arr[i];
                else
                    back += arr[i];
                if (++m > 2)
                    m = 0;
            }
            if (chest > biceps && chest > back)
                Console.WriteLine("chest");
            else if (biceps > chest && biceps > back)
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
        }
    }
}

using System;

namespace Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string[] line = Console.ReadLine().Split(' ');
            int[] exercices = new int[n];
            for (int i = 0; i < n; i++)
            {
                exercices[i] = Convert.ToInt32(line[i]);
            }
            int chest = 0;
            for (int i = 0; i < n; i = i + 3)
            {
                chest += exercices[i];
            }
            int biceps = 0;
            for (int i = 1; i < n; i = i + 3)
            {
                biceps += exercices[i];
            }
            int back = 0;
            for (int i = 2; i < n; i = i + 3)
            {
                back += exercices[i];
            }
            if (chest > biceps && chest > back)
            {
                Console.WriteLine("chest");
            }
            if (biceps > back && biceps > chest)
            {
                Console.WriteLine("biceps");
            }
            if(back > chest && back > biceps)
            {
                Console.WriteLine("back");
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace GregsWorkout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Int32.Parse(Console.ReadLine()), count = 0, chest = 0, biceps = 0, back = 0;
            int[] a = Array.ConvertAll(Console.ReadLine().Split(' '), Int32.Parse);
            int[] total;
            string[] name;
            for (int i = 0; i < n; i++)
            {
                count += 1;
                if (count == 1)
                    chest += a[i];
                else if (count == 2)
                    biceps += a[i];
                else if (count == 3)
                    back += a[i];
                if (count == 3)
                    count = 0;
            }
            total = new int[] { chest, biceps, back };
            name = new String[] { "chest", "biceps", "back" };
            Array.Sort(total, name);
            Console.WriteLine(name[2]);
            Console.ReadLine();
        }
    }
}

using System;
namespace A
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string[] str = Console.ReadLine().Split(' ');
            int chest = 0;
            int biceps = 0;
            int back = 0;
            int k = 0;
            for (int i = 0; i < n; i++)
            {
                if (k == 0)
                {
                    chest += int.Parse(str[i]);
                }
                else if (k == 1)
                {
                    biceps += int.Parse(str[i]);
                }
                else
                {
                    back += int.Parse(str[i]);
                }
                k++;
                if (k == 3)
                {
                    k = 0;
                }
            }
            if (chest>biceps && chest>back)
            {
                Console.Write("chest");
            }
            else if (biceps> back && biceps>chest)
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }
        }
    }
}

using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Globalization;

namespace Codeforces_156Div2
{
	class Program
	{

		public void Solve ()
		{
			int n = io.NextInt ();

			var sum = new int[3];

			for (int i = 0; i < n; ++i)
			{
				int a = io.NextInt ();
				sum[ i % 3 ] += a;
			}

			int best = 0;
			for (int i = 0; i < 3; ++i)
				if (sum[i] > sum[best])
					best = i;

			io.PrintLine (new String[]{"chest", "biceps", "back"}[best]);
		}

        #region Program

        private readonly MyIo io;

        public Program(MyIo io)
        {
            this.io = io;
        }

        public static void Main(string[] args)
        {
            using (MyIo io = new MyIo())
            {
                new Program(io).Solve();
            }
        }

        #endregion
    }

    #region MyIo

    internal class MyIo : IDisposable
    {
        private readonly TextReader reader;
        private readonly TextWriter writer;

        private string[] tokens;
        private int pointer;

		public MyIo ()
			: this(Console.In, Console.Out)
		{
		}

		public MyIo (TextReader reader, TextWriter writer)
		{
			this.reader = reader;
			this.writer = writer;
		}

        public string NextLine()
        {
            try
            {
                return reader.ReadLine();
            }
            catch (IOException)
            {
                return null;
            }
        }

        public string NextString()
        {
            try
            {
                while (tokens == null || pointer >= tokens.Length)
                {
                    tokens = NextLine().Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
                    pointer = 0;
                }
                return tokens[pointer++];
            }
            catch (IOException)
            {
                return null;
            }
        }

        public int NextInt()
        {
			int result;
			int.TryParse(NextString(), out result);
            return result;
        }

        public long NextLong()
        {
			long result;
			long.TryParse(NextString(), out result);
            return result;
        }

		public double NextDouble()
        {
			double result;
			double.TryParse(NextString(), out result);
            return result;
        }

        public T Next<T>()
        {
            return (T)Convert.ChangeType(NextString(), typeof(T));
        }

        public IEnumerable<T> NextSeq<T>(int n)
        {
			for (int i = 0; i < n; i++)
				yield return Next<T>();
        }

        public void Print(string format, params object[] args)
        {
            writer.Write(string.Format(CultureInfo.InvariantCulture, format, args));
        }

        public void PrintLine(string format, params object[] args)
        {
            Print(format, args);
            writer.WriteLine();
        }

        public void Print<T>(T o)
        {
            writer.Write(o);
        }

        public void PrintLine<T>(T o)
        {
            writer.WriteLine(o);
        }

        public void Close()
        {
            reader.Close();
            writer.Close();
        }

        void IDisposable.Dispose()
        {
            Close();
        }
    }

    #endregion
}

using System;
using System.Collections.Generic;
using System.Linq;
class Program
{
    static void Main()
    {
        int chest = 0, biceps = 0, back = 0;
        int counter = 0;
        string number = Console.ReadLine ();
        int n = Int32.Parse (number);
        string str = Console.ReadLine ();
        List<int> mains = new List<int> ();
        List<string> helpList = str.Split (' ').ToList();
        for (int i = 0; i < helpList.Count; i++) {
            mains.Add(Int32.Parse(helpList[i]));
        }
        int helpCounter = 0;
        for (int i = 1; i <= mains.Count; i++) {
            helpCounter++;
            if (helpCounter == 1)
                chest += mains [i - 1];
            else if (helpCounter == 2)
                biceps += mains [i - 1];
            else if (helpCounter == 3) {
                back += mains [i - 1];
                helpCounter = 0;
            }
        }
        if (chest > back && chest > biceps)
            Console.WriteLine ("chest");
        if (back > chest && back > biceps)
            Console.WriteLine ("back");
        if (biceps > chest && biceps > back)
            Console.WriteLine ("biceps");
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace SolvingAlgorithms
{
    class Program
    {
        static void Main(string[] args)
        {

            string input;
            input = Console.ReadLine();
            int n = Convert.ToInt32(input);
            input = Console.ReadLine();
            List<String> split = new List<string>(input.Split(' '));
            string current = "chest";
            int countChest = 0;
            int countBi = 0;
            int countBack = 0;

            while(split.Count>0)
            {
                int temp = Convert.ToInt32(split[0]);

                switch (current)
                {
                    case "chest": current = "biceps"; countChest += temp; break;
                    case "biceps": current = "back"; countBi += temp; break;
                    case "back": current = "chest"; countBack += temp; break;
                }
                split.RemoveAt(0);
            }

            if (countChest > countBi && countChest > countBack)
            {
                Console.WriteLine("chest");
            }
            else if (countBi > countChest && countBi > countBack)
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string[] r = Console.ReadLine().Split(' ');
            int chest = 0;
            int biceps = 0;
            int back = 0;
            for (int i = 0; i < n; i++)
            {
                int a = int.Parse(r[i]);
                if (i % 3 == 0) chest += a;
                else if (i % 3 == 1) biceps += a;
                else back += a;
            }
            int max = Math.Max(chest, Math.Max(biceps, back));
            if (max == chest) Console.WriteLine("chest");
            else if (max == biceps) Console.WriteLine("biceps");
            else Console.WriteLine("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Text;
using System.Linq;
using System.IO;
using System.Globalization;
using System.Collections;
using System.Text.RegularExpressions;

namespace Task
{

    #region MyIo

    internal class MyIo : IDisposable
    {
        private readonly TextReader inputStream;
        private readonly TextWriter outputStream = Console.Out;

        private string[] tokens;
        private int pointer;

        public MyIo()
#if  LOCAL_TEST
            : this(new StreamReader("input.txt"))
#else
            : this(System.Console.In)
#endif
        {

        }

        public MyIo(TextReader inputStream)
        {
            this.inputStream = inputStream;
        }

        public char NextChar()
        {
            try
            {
                return (char)inputStream.Read();
            }
            catch (IOException)
            {
                return '\0';
            }
        }

        public string NextLine()
        {
            try
            {
                return inputStream.ReadLine();
            }
            catch (IOException)
            {
                return null;
            }
        }

        public string NextString()
        {
            try
            {
                while (tokens == null || pointer >= tokens.Length)
                {
                    tokens = (NextLine() + string.Empty).Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
                    pointer = 0;
                }
                return tokens[pointer++];
            }
            catch (IOException)
            {
                return null;
            }
        }

        public int NextInt()
        {
            return Next<int>();
        }

        public long NextLong()
        {
            return Next<long>();
        }

        public T Next<T>()
        {
            var t = typeof(T);

            if (t == typeof(char))
                return (T)(object)NextChar();

            object s = NextString();

            if (t == typeof(string))
                return (T)s;

            return (T)Convert.ChangeType(s, typeof(T));
        }

        public IEnumerable<T> NextWhile<T>(Predicate<T> pred)
        {
            if (pred == null)
                yield break;

            T res = Next<T>();

            while (pred(res))
            {
                yield return res;

                res = Next<T>();
            }
        }

        public IEnumerable<T> NextSeq<T>(long n)
        {
            for (var i = 0; i < n; i++)
                yield return Next<T>();
        }

        public void Print(string format, params object[] args)
        {
            outputStream.Write(string.Format(CultureInfo.InvariantCulture, format, args));
        }

        public void PrintLine(string format, params object[] args)
        {
            Print(format, args);

            outputStream.WriteLine();
        }

        public void Print(bool o)
        {
            Print(o ? "yes" : "no");
        }

        public void PrintLine(bool o)
        {
            Print(o);

            outputStream.WriteLine();
        }

        public void Print<T>(T o)
        {
            outputStream.Write(Convert.ToString(o, CultureInfo.InvariantCulture));
        }

        public void PrintLine<T>(T o)
        {
            Print(o);

            outputStream.WriteLine();
        }

        public void Close()
        {
            inputStream.Close();
            outputStream.Close();
        }

        void IDisposable.Dispose()
        {
            Close();

#if  LOCAL_TEST
            Console.ReadLine();
#endif
        }
    }

    public static class ListExtensions
    {
        public static void Each<T>(this IEnumerable<T> self, Action<T> action)
        {
            foreach (var v in self)
                action(v);
        }

        public static IEnumerable<T> ToCycleEnumerable<T>(this IEnumerable<T> self)
        {
            if (self != null)
            {
                for (; ; )
                {
                    foreach (var x in self)
                        yield return x;
                }
            }
        }

        public static T CycleGet<T>(this IList<T> self, int index)
        {
            var c = self.Count;
            return self[(index % c + c) % c];
        }

        public static IList<T> Shuffle<T>(this IList<T> self)
        {
            var rnd = new Random(DateTime.Now.Millisecond);

            var n = self.Count;

            while (n > 1)
            {
                n--;
                var k = rnd.Next(n + 1);
                var value = self[k];
                self[k] = self[n];
                self[n] = value;
            }

            return self;
        }

        public static IList<IList<T>> UseForNew2D<T>(this T def, int fd, int sd)
        {
            var fdim = new T[fd][];

            for (int i = 0; i < fd; i++)
            {
                fdim[i] = new T[sd];
                Fill(fdim[i], def);
            }

            return fdim;
        }

        public static IList<T> Fill<T>(this IList<T> self, Func<T> fval)
        {
            for (var i = 0; i < self.Count; i++)
                self[i] = fval();

            return self;
        }

        public static IList<T> Fill<T>(this IList<T> self, T val)
        {
            return self.Fill(() => val);
        }

        public static long Hash<T>(this IList<T> self, Func<T, long> val = null)
        {
            return val != null ? self.Hash((t, current) => unchecked(current * 19L + val(t))) : self.Hash(HashOne);
        }

        public static long Hash<T>(this IList<T> self, Func<T, long, long> val)
        {
            return self.Aggregate(0L, (current, t) => unchecked(val(t, current)));
        }

        public static long HashOne<T>(this T self, long current)
        {
            return unchecked(current * 19L + (Equals(self, default(T)) ? 0 : self.GetHashCode()));
        }

        public static IList<T1> BuildSegTree<T1, T2>(this IList<T2> a, Func<T1, T1, T1> combine, Func<T2, T1> convert)
        {
            var t = new T1[a.Count << 2];

            a.BuildSegTree(t, 1, 0, a.Count - 1, combine, convert);

            return t;
        }

        private static void BuildSegTree<T1, T2>(this IList<T2> a, IList<T1> t, int v, int tl, int tr, Func<T1, T1, T1> combine, Func<T2, T1> convert)
        {
            if (tl == tr)
            {
                t[v] = convert(a[tl]);
            }
            else
            {
                int tm = (tl + tr) >> 1;

                BuildSegTree(a, t, v << 1, tl, tm, combine, convert);
                BuildSegTree(a, t, (v << 1) + 1, tm + 1, tr, combine, convert);

                t[v] = combine(t[v << 1], t[(v << 1) + 1]);
            }
        }
    }

    public static class P
    {
        public static P<T1, T2> Create<T1, T2>(T1 key, T2 val)
        {
            return new P<T1, T2>(key, val);
        }
    }

    public class P<T1, T2>
    {
        private class PComparer : IComparer<P<T1, T2>>
        {
            private readonly bool? byKey;

            public PComparer(bool? byKey)
            {
                this.byKey = byKey;
            }

            public int Compare(P<T1, T2> x, P<T1, T2> y)
            {
                x = x ?? new P<T1, T2>();
                y = y ?? new P<T1, T2>();

                if (byKey == true)
                    return Comparer<T1>.Default.Compare(x.Key, y.Key);
                else if (byKey == false)
                    return Comparer<T2>.Default.Compare(x.Value, y.Value);
                else
                {
                    var tr = Comparer<T1>.Default.Compare(x.Key, y.Key);

                    if (tr != 0)
                        tr = Comparer<T2>.Default.Compare(x.Value, y.Value);

                    return tr;
                }
            }
        }

        public P()
        {
        }

        public P(T1 key, T2 val)
        {
            this.Key = key;
            this.Value = val;
        }

        public T1 Key
        {
            get;
            set;
        }

        public T2 Value
        {
            get;
            set;
        }

        public P<T1, T2> Clone()
        {
            return new P<T1, T2>(Key, Value);
        }

        public static IComparer<P<T1, T2>> KeyComparer
        {
            get { return new PComparer(true); }
        }

        public static IComparer<P<T1, T2>> ValueComparer
        {
            get { return new PComparer(false); }
        }

        public static implicit operator T1(P<T1, T2> obj)
        {
            return obj.Key;
        }

        public static implicit operator T2(P<T1, T2> obj)
        {
            return obj.Value;
        }

        public P<T1, T2> SetKey(T1 key)
        {
            Key = key;
            return this;
        }

        public P<T1, T2> SetValue(T2 value)
        {
            Value = value;
            return this;
        }

        public override string ToString()
        {
            return string.Format("Key: {0}, Value: {1}", Key, Value);
        }

        public override bool Equals(object obj)
        {
            var co = obj as P<T1, T2>;

            return co != null && co.GetHashCode() == GetHashCode();
        }

        public override int GetHashCode()
        {
            int hash = 17;
            hash = hash * 31 + ((Equals(Key, default(T1))) ? 0 : Key.GetHashCode());
            hash = hash * 31 + ((Equals(Value, default(T1))) ? 0 : Value.GetHashCode());
            return hash;

        }
    }

    #endregion

    internal class Program
    {
        #region Program

        private readonly MyIo io;

        public Program(MyIo io)
        {
            this.io = io;
        }

        public static void Main(string[] args)
        {
            using (MyIo io = new MyIo())
            {
                new Program(io)
                    .Solve();
            }
        }

        #endregion
        public const long MOD = 1000000007;
        public const double EPS = 1e-14;

        private void Solve()
        {
            var n = io.NextInt();

            var keys = new[] {"chest", "biceps", "back"};
            var h = keys.ToDictionary(x => x, x => 0);

            for (int i = 0; i < n; i++)
            {
                h[keys[i%3]] += io.NextInt();
            }

            io.Print(h.OrderByDescending(x=>x.Value).FirstOrDefault().Key);

        }

    }

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CodeForces
{
    class Program_R156_Div2_A
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string[] s = (Console.ReadLine().Split());
            int[] b = new int[Math.Max(n,3)];
            for (int i = 0; i < n; i++)
                b[i] = Convert.ToInt32(s[i]);

            for (int j = 3; j < n; j++)
                b[j % 3] += b[j];

            string ans = "back";
            if (b[0] > b[1] && b[0] > b[2])
                ans = "chest";
            else if (b[1] > b[0] && b[1] > b[2])
                ans = "biceps";

            Console.WriteLine(ans);
        }
    }
}

using System;
using System.Linq;

class Program
{
        static void Main(string[] args)
        {
            int n;
            string t;
            int biceps = 0;
            int chest = 0;
            int back = 0;

            t = Console.ReadLine();

            int.TryParse(t, out n);

            int[] a = new int[n];
            t = Console.ReadLine();

            string[] sa = t.Split(' ');

            for (int i = 0; i < n; i++)
            {
                int.TryParse(sa[i], out a[i]);
            }

            int buf = 1;

            for (int i = 0; i < n; i++)
            {
                switch (buf)
                {
                    case 1:
                        chest += a[i];
                        break;
                    case 2:
                        biceps += a[i];
                        break;
                    case 3:
                        back += a[i];
                        break;
                }
                buf++;
                if (buf == 4) buf = 1;
            }

            if (chest > biceps && chest > back) Console.WriteLine("chest");
            if (biceps > chest && biceps > back) Console.WriteLine("biceps");
            if (back > chest && back > biceps) Console.WriteLine("back");
        }
}

using System;

class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        int[] arr = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);

        string result = "";
        int chestCount = 0;
        int bicepsCount = 0;
        int backCount = 0;
        for (int i = 0; i < n; i++)
        {
            int ex = i % 3;
            if (ex == 0)
                chestCount += arr[i];
            else if (ex == 1)
                bicepsCount += arr[i];
            else if (ex == 2)
                backCount += arr[i];
        }
        if (chestCount > bicepsCount && chestCount > backCount)
            Console.WriteLine("chest");
        else if (bicepsCount > chestCount && bicepsCount > backCount)
            Console.WriteLine("biceps");
        else if (backCount > chestCount && backCount > bicepsCount)
            Console.WriteLine("back");
    }
}

using System;

namespace vlad.a
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string s = Console.ReadLine();
            string[] ss = s.Split(' ');
            int chest, biceps, back;
            chest = biceps = back = 0;
            for(int i = 0; i < n; i++)
            {
                switch(i % 3)
                {
                    case 0:
                        chest += Convert.ToInt32(ss[i]);
                        break;
                    case 1:
                        biceps += Convert.ToInt32(ss[i]);
                        break;
                    case 2:
                        back += Convert.ToInt32(ss[i]);
                        break;
                }
            }
            Console.WriteLine((chest > biceps) ? ((chest > back) ? "chest" : "back") : ((biceps > back) ? "biceps" : "back"));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Globalization;
using System.Threading;
using System.Collections;
using System.IO;

namespace AcmSolution
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            Thread.CurrentThread.CurrentCulture = CultureInfo.InvariantCulture;
            //Console.SetIn(new StreamReader("gcd.in"));
           // Console.SetOut(new StreamWriter("gcd.out"));
            Do();
            //Console.Out.Close();
            Console.ReadLine();
        }

        private static void Do()
        {
            int n = GetInt();
            int[] a = GetInts();
            int sumChest = 0;
            int sumBiceps = 0;
            int sumBack = 0;
            string answer = "back";
            for (int i = 0; i < n; i += 3)
            {
                sumChest = sumChest + a[i];
            }
            for (int i = 1; i < n; i += 3)
            {
                sumBiceps = sumBiceps + a[i];
            }
            for (int i = 2; i < n; i += 3)
            {
                sumBack = sumBack + a[i];
            }
            if (sumChest > sumBiceps && sumChest > sumBack)
                answer = "chest";
            else if (sumBiceps > sumChest && sumBiceps > sumBack)
                answer = "biceps";

            Console.WriteLine(answer);
        }

     #region Utils
        private const double Epsilon = 0.00000001;

        private static string GetStr()
        {
            return Console.ReadLine();
        }

        private static string[] GetStrs()
        {
            return GetStr().Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
        }

        private static string[] GetStrs(int cnt)
        {
            var s = new string[cnt];
            for (var i = 0; i < cnt; ++i)
                s[i] = GetStr();
            return s;
        }

        private static int GetInt()
        {
            return int.Parse(GetStr());
        }

        private static void GetInts(out int a, out int b)
        {
            var q = GetInts();
            a = q[0];
            b = q[1];
        }

        private static void GetInts(out int a, out int b, out int c)
        {
            var q = GetInts();
            a = q[0];
            b = q[1];
            c = q[2];
        }

        private static int[] GetInts()
        {
            var s = GetStrs();
            var a = new int[s.Length];
            for (var i = 0; i < s.Length; ++i)
                a[i] = int.Parse(s[i]);
            return a;
        }

        private static long GetLong()
        {
            return long.Parse(GetStr());
        }

        private static IEnumerable<long> GetLongs()
        {
            return GetStrs().Select(long.Parse);
        }

        private static void WriteDouble<T>(T d)
        {
            Console.WriteLine(string.Format("{0:0.000000000}", d).Replace(',', '.'));
        }

        private static void WL<T>(T s)
        {
            Console.WriteLine(s);
        }

        private static void W<T>(T s)
        {
            Console.Write(s);
        }

        private static void Assert(bool b)
        {
            if (!b) throw new Exception();
        }

        private static void Swap<T>(ref T a, ref T b)
        {
            var temp = a;
            a = b;
            b = temp;
        }

        #endregion
    }
}

using System;
using System.Text;

namespace pr111
{
    class Program
    {
        public static void Main(string[] args)
        { int a,b,c,n;string s;
            n=Convert.ToInt16(Console.ReadLine());
            int[] arr;
            arr= new int[24];
            a = 0; b =0; c =0;
            string[] line=Console.ReadLine().Split();
            for (int i=0; i<line.Length; i++) {arr[i]=Convert.ToInt16(line[i]);}
            for (int i=1; i<24; i++) {if(i%3==1){a+=arr[i-1];} if(i%3==2){b+=arr[i-1];} if(i%3==0){c+=arr[i-1];}}
            if (a>=b&&a>=c) {s="chest";} else {if(b>c){s="biceps";} else {s="back";}}
            Console.WriteLine(Convert.ToString(s));
           // Console.ReadKey(true);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace CodeForces
{
    class MainClass
    {
        public static void Main(string[] args)
        {
            var number = Int32.Parse(Console.ReadLine());
            var exercises = Console.ReadLine();
            var dataStr = exercises.Split(' ');
            List<int> data = dataStr.Select(int.Parse).ToList();
            Console.WriteLine(MostTrainedMuscle(number, data));
        }
        private static string MostTrainedMuscle(int number, List<int> data)
        {
            int chestExerciseCount = 0, bicepsExerciseCount = 0, backExcersiceCount = 0;

            for (var i = 0; i < number;)
            {
                int windows = number / 3;
                int remaining = number % 3;
                while (windows-- > 0)
                {
                    int chest = data[i];
                    int biceps = data[i + 1];
                    int back = data[i + 2];

                    chestExerciseCount += chest;
                    bicepsExerciseCount += biceps;
                    backExcersiceCount += back;

                    i += 3;
                }

                if (remaining != 0)
                {
                    i -= 1;
                    if (remaining == 1)
                    {
                        chestExerciseCount += data[i + 1];
                        break;
                    }

                    if (remaining == 2)
                    {
                        chestExerciseCount += data[i + 1];
                        bicepsExerciseCount += data[i + 2];
                        break;
                    }
                }
            }
            var result = Maxof3Numbers(chestExerciseCount, bicepsExerciseCount, backExcersiceCount);
            return result;
        }

        private static string Maxof3Numbers(int chestExerciseCount, int bicepsExerciseCount, int backExcersiceCount)
        {
            if (chestExerciseCount > bicepsExerciseCount && chestExerciseCount > backExcersiceCount)
                return "chest";
            if (bicepsExerciseCount > chestExerciseCount && bicepsExerciseCount > backExcersiceCount)
                return "biceps";
            if (backExcersiceCount > chestExerciseCount && backExcersiceCount > bicepsExerciseCount)
                return "back";
            return string.Empty;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace CodeForces
{
    class Program
    {
        public static void Main(string[] args)
        {
            var number = Int32.Parse(Console.ReadLine());
            var exercises = Console.ReadLine();
            var dataStr = exercises.Split(' ');
            List<int> data = dataStr.Select(int.Parse).ToList();
            Console.WriteLine(MostTrainedMuscle(number, data));
        }

        private static string MostTrainedMuscle(int number, List<int> data)
        {
            int chestExerciseCount = 0, bicepsExerciseCount = 0, backExcersiceCount = 0;

            for (var i = 0; i < number;)
            {
                int windows = number / 3;
                int remaining = number % 3;
                while (windows-- > 0)
                {
                    int chest = data[i];
                    int biceps = data[i + 1];
                    int back = data[i + 2];

                    chestExerciseCount += chest;
                    bicepsExerciseCount += biceps;
                    backExcersiceCount += back;

                    i += 3;
                }

                if (remaining != 0)
                {
                    if (remaining == 1)
                    {
                        chestExerciseCount += data[i];
                        break;
                    }

                    if (remaining == 2)
                    {
                        chestExerciseCount += data[i];
                        bicepsExerciseCount += data[i + 1];
                        break;
                    }
                }
            }
            var result = Maxof3Numbers(chestExerciseCount, bicepsExerciseCount, backExcersiceCount);
            return result;
        }

        private static string Maxof3Numbers(int chestExerciseCount, int bicepsExerciseCount, int backExcersiceCount)
        {
            if (chestExerciseCount > bicepsExerciseCount && chestExerciseCount > backExcersiceCount)
                return "chest";
            if (bicepsExerciseCount > chestExerciseCount && bicepsExerciseCount > backExcersiceCount)
                return "biceps";
            if (backExcersiceCount > chestExerciseCount && backExcersiceCount > bicepsExerciseCount)
                return "back";
            return string.Empty;
        }
    }
}

using System;

namespace D2Problem1
{
    class Program
    {
        static void Main(string[] args)
        {
            int chest=0;
            int biceps = 0;
            int back = 0;
            int n = int.Parse(Console.ReadLine());
            int[] input = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
            for (int i = 0; i < n; i += 3)
                chest += input[i];
            for (int i = 1; i < n; i += 3)
                biceps += input[i];
            for (int i = 2; i < n; i += 3)
                back += input[i];
            if(chest>biceps&&chest>back)
                Console.WriteLine("chest");
            else if(biceps>chest&&biceps>back)
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");

        }
    }
}

using System;

namespace ConsoleApplication32
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Int32.Parse(Console.ReadLine());
            int[] a = new int[n];
            string str = Console.ReadLine();
            string[] subString = str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            int b = 0;
            int c = 0;
            int d = 0;
            for (int i = 0; i < n; i++)
            {
                a[i] = Convert.ToInt32(subString[i]);
            }
            for (int i = 0; i < n; i = i + 3)
            {
                b = b + a[i];
            }
            for (int i = 1; i < n; i = i + 3)
            {
                c = c + a[i];
            }
            for(int i = 2; i < n; i = i + 3)
            {
                d = d + a[i];
            }
            if (b > c && b > d)
            {
                Console.WriteLine("chest");
            }
            else if (c > d)
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace Codeforce {
    class Program {

        public class Muscle {
            public int Training = 0;
            public string Name = "";

            public override string ToString() {
                return Name;
            }

            public Muscle CompareTo(Muscle obj) {
                return this.Training > obj.Training ? this : (this.Training == obj.Training) ? this : obj;
            }
        }

        static void Main() {
            var n = Convert.ToInt32(Console.ReadLine());
            var tmpArr = Console.ReadLine().Split(' ');
            var list = new List<int>();
            for (int i = 0; i < n; i++) {
                list.Add(int.Parse(tmpArr[i]));
            }

            var chest = new Muscle() {
                Name = "chest"
            };
            var biceps = new Muscle() {
                Name = "biceps"
            };
            var back = new Muscle() {
                Name = "back"
            };

            for (int i = 0; i < n; i += 3) {
                chest.Training += list[i];
            }

            for (int i = 1; i < n; i += 3) {
                biceps.Training += list[i];
            }

            for (int i = 2; i < n; i += 3) {
                back.Training += list[i];
            }

            Console.WriteLine(chest.CompareTo(biceps.CompareTo(back)));
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _255A
{
    class Program
    {
        static void Main(string[] args)
        {
            int chest = 0, biceps = 0, back = 0;
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split().Select(_ => int.Parse(_)).ToArray();
            for(int i = 0;i<n;i++)
            {
                switch((i+1)%3)
                {
                    case 1:chest += a[i];break;
                    case 2:biceps += a[i]; break;
                    case 0:back += a[i]; break;
                }
            }
            if (chest < biceps)
                Console.WriteLine(biceps > back ? "biceps" : "back");
            else
                Console.WriteLine(chest > back ? "chest" : "back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CFR156
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] ans = new int[3];
            int[] a = new int[n];
            string[] input = Console.ReadLine().Split(' ');
            for (int i = 0; i < n; i++)
                a[i] = int.Parse(input[i]);
            for (int i = 0,j=0; i < n; i++)
            {
                ans[j] += a[i];
                if (j == 2) j = -1;
                j++;
            }
            if (ans[0] > ans[1]&&ans[0]>ans[2])
                Console.WriteLine("chest");
            if (ans[1] > ans[0] && ans[1] > ans[2])
                Console.WriteLine("biceps");
            if (ans[2] > ans[0] && ans[2] > ans[1])
                Console.WriteLine("back");
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

namespace ProjectContest
{
    class Test
    {
        static void Main()
        {
            int n = Convert.ToInt32(Console.ReadLine());
            int[] ex = new int[3];
            var a = Array.ConvertAll(Console.ReadLine().Split(), Convert.ToInt32);
            for(int i=0;i<n;i++)
            {
                ex[i % 3] += a[i];
            }
            if (ex.Max() == ex[0]) Console.WriteLine("chest");
            else if (ex.Max() == ex[1]) Console.WriteLine("biceps");
            else Console.WriteLine("back");
        }
    }
}

using System;

namespace codeforces{
  public class task{
    static void Main(){
      int n;
      int []tr={0,0,0};
      n=Convert.ToInt32(Console.ReadLine());
      int []training=new int[n];
      string[] str = Console.ReadLine().Split(new char[] { ' ', '\n', '\t' }, StringSplitOptions.RemoveEmptyEntries);
      for(int i=0;i<n;i++){
        training[i]=Convert.ToInt32(str[i]);
      }
      int k=1;
      for(int i=0;i<n;i++,k++){
        if(k==1){
          tr[0]+=training[i];
        }else{
          if(k==2){
            tr[1]+=training[i];
          }else if(k==3){
            tr[2]+=training[i];
            k=0;
          }
        }
      }
      if(tr[0]>tr[1]&&tr[0]>tr[2]){
        Console.WriteLine("chest");
      }else{
        if(tr[1]>tr[0]&&tr[1]>tr[2]){
          Console.WriteLine("biceps");
        }else{
          Console.WriteLine("back");
        }
      }
    }
  }
}

using System;
class Program
{
    static void Main()
    {
        int n = int.Parse(Console.ReadLine());
        int[] args = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        int biceps = 0, chest = 0, back = 0;
        for (int i = 0; i < args.Length; i++)
        {
            if (i % 3 == 0)
                chest += args[i];
            if ((i - 1) % 3 == 0)
                biceps += args[i];
            if ((i - 2) % 3 == 0)
                back += args[i];
        }
        if (chest > biceps && chest > back)
            Console.WriteLine(nameof(chest));
        if (biceps > chest && biceps > back)
            Console.WriteLine(nameof(biceps));
        if (back > chest && back > biceps)
            Console.WriteLine(nameof(back));
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace forcesGym
{
    class Program
    {
        static void Main(string[] args)
        {
            String xaxa = Console.ReadLine();
            int n = int.Parse(xaxa);

            int[] arr = new int[3];
            Array.Clear(arr,0,3);

            String babu = Console.ReadLine();
            String[] hadd=babu.Split(' ');
            for (int i = 0; i < n; i++)
            {
                int iRon = i % 3;

                int val = int.Parse(hadd[i]);

                arr[iRon] += val;

            }

            String res;

            if (arr[0] > arr[1] && arr[0] > arr[2])
                res = "chest";
            else if (arr[1] > arr[0] && arr[1] > arr[2])
                res = "biceps";
            else
                res = "back";

            Console.WriteLine(res);

        }
    }
}

using System;

namespace GregsWorkout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());

            string [] input = Console.ReadLine().Split(new char[]{' '}, StringSplitOptions.None);

            int [] train = new int[3];
            for (int i=0; i<n; i++){
                train[i%3] += int.Parse(input[i]);
            }

            int max = int.MinValue;
            int maxIndex = 0;
            for (int i=0; i<3; i++){
                if (train[i] > max){
                    max = train[i];
                    maxIndex = i;
                }
            }

            switch(maxIndex){
                case 0:
                    Console.WriteLine("chest");
                    break;
                case 1:
                    Console.WriteLine("biceps");
                    break;
                case 2:
                    Console.WriteLine("back");
                    break;
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Codeforces
{
	class Program
	{
		static void Main(string[] args)
		{
			string input1 = Console.ReadLine();
			string input2 = Console.ReadLine();

			//var inputs1 = input1.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse).ToArray();
			var inputs2 = input2.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries).Select(int.Parse);

			var n = int.Parse(input1);
			var chest = inputs2.Where((item, index) => index % 3 == 0).Sum();
			var biceps = inputs2.Where((item, index) => index % 3 == 1).Sum();
			var back = inputs2.Where((item, index) => index % 3 == 2).Sum();

			var maxBicepsBack = Math.Max(biceps, back);
			if (chest > maxBicepsBack)
			{
				Console.WriteLine("chest");
			}
			else
			{
				var result = maxBicepsBack == biceps ? "biceps" : "back";
				Console.WriteLine(result);
			}
		}

		//private static long GCD(long a, long b)
		//{
		//	long max = Math.Max(a, b);
		//	long min = Math.Min(a, b);

		//	if (min == 0)
		//	{
		//		return max;
		//	}

		//	a = min;
		//	b = max % min;
		//	return GCD(a, b);
		//}

		//private static long LCM(long a, long b)
		//{
		//	return Math.Abs(a * b) / GCD(a, b);
		//}

		//private static int Length(short[] a)
		//{
		//	int firstItemIndex = 0;
		//	for (int i = 0; i < a.Length; i++)
		//	{
		//		if (a[i] == 0)
		//		{
		//			continue;
		//		}

		//		firstItemIndex = i;
		//		break;
		//	}

		//	return a.Length - firstItemIndex;
		//}

		//private static short[] Subtract(short[] a, short[] b)
		//{
		//	if (a.Length != b.Length)
		//	{
		//		throw new ArgumentException();
		//	}

		//	short[] result = new short[a.Length];
		//	Array.Copy(a, result, a.Length);
		//	for (int i = result.Length - 1; i >= 0; i--)
		//	{
		//		if (result[i] < b[i])
		//		{
		//			int j = i - 1;
		//			while (result[j] == 0)
		//			{
		//				result[j--] = 9;
		//			}

		//			result[j]--;
		//			result[i] += 10;
		//		}

		//		result[i] -= b[i];
		//	}

		//	return result;
		//}

		//private static short[] Multiply(short[] a, int b)
		//{
		//	short[] result = new short[a.Length];
		//	for (int i = a.Length - 1; i > 0; i--)
		//	{
		//		int temp = a[i] * b;
		//		result[i] = (short)(result[i] + temp % 10);
		//		result[i - 1] = (short)(result[i - 1] + temp / 10);
		//	}

		//	return result;
		//}

		//private static int Mod(short[] a, int b)
		//{
		//	int rest = 0, i = 0;
		//	while (i < a.Length)
		//	{
		//		int d = 10 * rest + a[i];
		//		while (d < b && i < a.Length - 1)
		//		{
		//			d = 10 * d + a[++i];
		//		}

		//		rest = d % b;
		//		i++;
		//	}

		//	return rest;
		//}

		//private static short[] Divide(short[] a, int b)
		//{
		//	short[] result = new short[a.Length];
		//	int rest = 0, i = 0;
		//	while (i < a.Length)
		//	{
		//		int d = 10 * rest + a[i];
		//		while (d < b && i < a.Length - 1)
		//		{
		//			d = 10 * d + a[++i];
		//		}

		//		result[i] = (short)(d / b);
		//		rest = d % b;
		//		i++;
		//	}

		//	return result;
		//}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;

namespace CF {

    class Program {

        static void Main(string[] args) {

#if DEBUG
            TextReader reader = new StreamReader("../../input.txt");
#else
			TextReader reader = Console.In;
#endif

            reader.ReadLine();
            var innn = reader.ReadLine().Split(' ').Select(int.Parse).ToArray();

            long[] trains = { 0, 0, 0 };

            for (int i = 0; i < innn.Length; i++) {
                trains[i % 3] += innn[i];
            }

            var m = trains.Max();
            if (trains[0] == m) {
                Console.WriteLine("chest");
            }
            if (trains[1] == m) {
                Console.WriteLine("biceps");
            }
            if (trains[2] == m) {
                Console.WriteLine("back");
            }

#if DEBUG
            Console.ReadKey();
#endif

        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace prob6_Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            var exerciseasNumber = Convert.ToInt32(Console.ReadLine());
            var exercises = Console.ReadLine();
            var exercisesSplit = exercises.Split(' ');
            int chest = 0;
            int biceps = 0;
            int back = 0;
            int newNumber = 0;

            for (var Number = 0; Number < exerciseasNumber; Number++)
            {
                if ((Number+1)%3 == 1)
                {
                    newNumber = Convert.ToInt32(exercisesSplit[Number]);
                    chest = chest + newNumber;
                }
                else if ((Number+1)%3 == 2)
                {
                    newNumber = Convert.ToInt32(exercisesSplit[Number]);
                    biceps = biceps + newNumber;
                }
                else if ((Number+1)%3 == 0)
                {
                    newNumber = Convert.ToInt32(exercisesSplit[Number]);
                    back = back + newNumber;
                }
            }

            if(chest > biceps && chest > back)
            {
                Console.WriteLine("chest");
            }
            if( biceps > chest && biceps > back)
            {
                Console.WriteLine("biceps");
            }
            if(back > chest && back > biceps)
            {
                Console.WriteLine("back");
            }
        }
        }
    }

/*

 */
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using System.Diagnostics;

public class Solver
{
    public void Solve()
    {
        int n = ReadInt();
        int[] A = ReadIntArray();
        int chest = 0;
        int biceps = 0;
        int back = 0;
        for (int i = 0; i < n; i++) {
            if (i % 3 == 0)
                chest += A[i];
            else if (i % 3 == 1)
                biceps += A[i];
            else
                back += A[i];
        }
        if (chest > Math.Max(biceps, back))
            Write("chest");
        else if (biceps > Math.Max(chest, back))
            Write("biceps");
        else
            Write("back");

    }

    #region Main

    protected static TextReader reader;
    protected static TextWriter writer;
    static void Main()
    {
        Debug.Listeners.Clear();
        Debug.Listeners.Add(new ConsoleTraceListener());
        Trace.Listeners.Clear();
        Trace.Listeners.Add(new ConsoleTraceListener());

        reader = new StreamReader(Console.OpenStandardInput());
        writer = new StreamWriter(Console.OpenStandardOutput());
        new Solver().Solve();
        reader.Close();
        writer.Close();
    }

    #endregion

    #region Read / Write
    private static Queue<string> currentLineTokens = new Queue<string>();
    private static string[] ReadAndSplitLine() { return reader.ReadLine().Split(new[] { ' ', '\t', }, StringSplitOptions.RemoveEmptyEntries); }
    public static string ReadToken() { while (currentLineTokens.Count == 0)currentLineTokens = new Queue<string>(ReadAndSplitLine()); return currentLineTokens.Dequeue(); }
    public static int ReadInt() { return int.Parse(ReadToken()); }
    public static long ReadLong() { return long.Parse(ReadToken()); }
    public static double ReadDouble() { return double.Parse(ReadToken(), CultureInfo.InvariantCulture); }
    public static int[] ReadIntArray() { return ReadAndSplitLine().Select(int.Parse).ToArray(); }
    public static long[] ReadLongArray() { return ReadAndSplitLine().Select(long.Parse).ToArray(); }

    public static int[][] ReadIntMatrix(int numberOfRows) { int[][] matrix = new int[numberOfRows][]; for (int i = 0; i < numberOfRows; i++)matrix[i] = ReadIntArray(); return matrix; }
    public static int[][] ReadAndTransposeIntMatrix(int numberOfRows)
    {
        int[][] matrix = ReadIntMatrix(numberOfRows); int[][] ret = new int[matrix[0].Length][];
        for (int i = 0; i < ret.Length; i++) { ret[i] = new int[numberOfRows]; for (int j = 0; j < numberOfRows; j++)ret[i][j] = matrix[j][i]; } return ret;
    }
    public static string[] ReadLines(int quantity) { string[] lines = new string[quantity]; for (int i = 0; i < quantity; i++)lines[i] = reader.ReadLine().Trim(); return lines; }
    public static void WriteArray<T>(IEnumerable<T> array) { writer.WriteLine(string.Join(" ", array)); }
    public static void Write(params object[] array) { WriteArray(array); }
    public static void WriteLines<T>(IEnumerable<T> array) { foreach (var a in array)writer.WriteLine(a); }
    private class SDictionary<TKey, TValue> : Dictionary<TKey, TValue>
    {
        public new TValue this[TKey key]
        {
            get { return ContainsKey(key) ? base[key] : default(TValue); }
            set { base[key] = value; }
        }
    }
    private static T[] Init<T>(int size) where T : new() { var ret = new T[size]; for (int i = 0; i < size; i++)ret[i] = new T(); return ret; }
    #endregion
}

using System;
class CFR156D2A
{
	static void Main()
	{
		int chestCount = 0;
		int bicepsCount = 0;
		int backCount = 0;
		int n = int.Parse(Console.ReadLine());
		string[] data = Console.ReadLine().Split(' ');
		int checkIndex = 0;
		for (int i = 0; i < n; i++)
		{
			if (checkIndex == 0)
			{
				chestCount += int.Parse(data[i]);
				checkIndex++;
			}
			else if (checkIndex == 1)
			{
				bicepsCount += int.Parse(data[i]);
				checkIndex++;
			}
			else
			{
				backCount += int.Parse(data[i]);
				checkIndex = 0;
			}
		}
		if ((chestCount > bicepsCount) && (chestCount > backCount))
		{
			Console.WriteLine("chest");
		}
		else if ((bicepsCount > chestCount) && (bicepsCount > backCount))
		{
			Console.WriteLine("biceps");
		}
		else
		{
			Console.WriteLine("back");
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp10
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int[] y = new int[3];
            for (int i = 0; i < n; i++)
            {
                if ((i+1)%3==1)
                {
                    y[0]+=l[i];
                    continue;
                }
                else if ((i+1)%3==2)
                {
                    y[1]+=l[i];
                    continue;
                }
                else
                {
                    y[2]+=l[i];
                }
            }
            if (y.Max() == y[0])
            {
                Console.WriteLine("chest");
            }
            else if (y.Max() ==y[1])
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CF._255A
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int chest = 0, biceps = 0, back = 0;
            string[] a = Console.ReadLine().Split();
            for (int i = 0; i < n; i++)
                if (i % 3 == 0)
                    chest += int.Parse(a[i]);
                else if (i % 3 == 1)
                    biceps += int.Parse(a[i]);
                else
                    back += int.Parse(a[i]);
            if (chest >= biceps && chest >= back)
                Console.WriteLine("chest");
            else if (biceps >= chest && biceps >= back)
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.IO;
using System.Linq;
using System.Runtime.Remoting.Messaging;
using System.Security;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;
using System.Xml;

namespace codeforces
{
	class Program
	{
		public class User
		{
			public int c;

			public int r;
		}

		public class Comparer : IComparer<User>
		{
			public int Compare(User x, User y)
			{
				if (x.c < y.c)
					return -1;
				return 1;
			}
		}

		public static long getGcd(long a, long b)
		{
			if (b == 0)
				return a;
			return getGcd(b, a % b);
		}

		public static void WriteYESNO(bool x, string yes = "YES", string no = "NO")
		{
			if (x)
				Console.WriteLine(yes);
			else
			{
				Console.WriteLine(no);
			}
		}

		public static string GetString()
		{
			return Console.ReadLine();
		}

		public static List<int> getList()
		{
			var s = Console.ReadLine();
			return s.Split(' ').Select(int.Parse).ToList();
		}

		public static int Min(int x, int y)
		{
			return Math.Min(x, y);
		}

		public static int Max(int x, int y)
		{
			return Math.Max(x, y);
		}

		public static int Abs(int x)
		{
			return Math.Abs(x);
		}

		public static int getInt()
		{
			var s = Console.ReadLine();
			return int.Parse(s);
		}

		public static bool Equal(int x, int y, int x1, int y1)
		{
			return x == x1 && y == y1;
		}

		public class Vertex
		{
			public List<int> edges;

			public int ct;

			public Vertex()
			{
				ct = 0;
				edges = new List<int>();
				for (var i = 0; i < 26; ++i)
					edges.Add(0);
			}
		}

		private static void Main(string[] args)
		{
/*			var input = new StreamReader("input.txt");
			var output = new StreamWriter("output.txt");*/
			var n = getInt();
			var l = getList();
			var l1 = new List<int>();
			l1.Add(0);
			l1.Add(0);
			l1.Add(0);
			for (var i = 0; i < n; ++i)
				l1[i % 3] += l[i];
			var max = l1.Max();
			if (l1[0] == max)
				Console.WriteLine("chest");
			if (l1[1] == max)
				Console.WriteLine("biceps");
			if (l1[2] == max)
				Console.WriteLine("back");
			/*			input.Close();
			output.Close();*/
		}
	}
}

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApplication16
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            int n = Int32.Parse(Console.ReadLine());

            int spin = 0;
            int bicz = 0;
            int grud = 0;

            string fd = Console.ReadLine();

            int[] arrayiNT = new int[n];

            for (int i = 1; i < n + 1; i++)
            {
                arrayiNT[i - 1] = Int32.Parse(fd.Split(' ')[i - 1]);
                if (i%3 == 0)
                {
                    spin += arrayiNT[i - 1];
                }
                if (i%3 == 1)
                {
                    grud += arrayiNT[i - 1];
                }
                if (i%3 == 2)
                {
                    bicz += arrayiNT[i - 1];
                }
            }

            Dictionary<string, int> slovar = new Dictionary<string, int>()
            {
                {"back", spin},
                {"biceps", bicz},
                {"chest", grud}
            };
            List<int> upra = new List<int>();

            upra.Add(spin);
            upra.Add(grud);
            upra.Add(bicz);
            string dfgs = slovar.FirstOrDefault(el => el.Value == upra.Max()).Key;
            Console.WriteLine(dfgs);

        }
    }
}

using System;
using System.Linq;

namespace _255A
{
    class Program
    {
        static void Main()
        {
            var n = int.Parse(Console.ReadLine());
            var array = Console.ReadLine().Split().Select(int.Parse).ToArray();
            var counter = 0;
            int chest = 0, biceps = 0, back = 0;
            for (int i = 0; i < n; i++)
            {
                switch (counter)
                {
                    case 0:
                        chest += array[i];
                        break;
                    case 1:
                        biceps += array[i];
                        break;
                    case 2:
                        back += array[i];
                        break;
                }
                counter++;
                if (counter > 2) counter = 0;
            }

            if (chest > biceps && chest > back) Console.WriteLine("chest");
            else if (biceps > chest && biceps > back) Console.WriteLine("biceps");
            else Console.WriteLine("back");
        }
    }
}

using System;
using System.Linq;
using System.Collections.Generic;
using System.Text;

namespace MakeCalendar
{
    class MainClass
    {

        static int ReadIntLine()
        {
            return int.Parse(Console.ReadLine());
        }

        static void ReadInt(ref int a)
        {
            a = ReadIntArrayLine()[0];
        }

        static void ReadInts(ref int a, ref int b)
        {
            var x = ReadIntArrayLine();
            a = x[0]; b = x[1];
        }

        static void ReadInts(ref int a, ref int b, ref int c)
        {
            var x = ReadIntArrayLine();
            a = x[0]; b = x[1]; c = x[2];
        }

        static void ReadInts(ref int a, ref int b, ref int c, ref int d)
        {
            var x = ReadIntArrayLine();
            a = x[0]; b = x[1]; c = x[2]; d = x[3];
        }

        static int[] ReadIntArrayLine()
        {
            char[] sep = { ' ' };
            return Console.ReadLine().Split(sep, StringSplitOptions.RemoveEmptyEntries).Select(x => int.Parse(x)).ToArray();
        }

        static void PrintLn(object obj)
        {
            Console.WriteLine(obj.ToString());
        }

        public static string Reverse(string s)
        {
            char[] charArray = s.ToCharArray();
            Array.Reverse(charArray);
            return new string(charArray);
        }

        public static void PrintLnCollection<T>(IEnumerable<T> col)
        {
            PrintLn(string.Join(" ",col));
        }

//----------------------------------------------------------------------------

        static void Main(string[] args)
        {
            int n = 0, c = 0;

            n = ReadIntLine() ;

            int[] a = ReadIntArrayLine();

            int chest = a.Where((x, xi) => xi % 3 == 0).Sum();
            int biceps = a.Where((y, yi) => yi % 3 == 1).Sum();
            int back = a.Where((z, zi) => zi % 3 == 2).Sum();

            if (chest == Math.Max(chest, Math.Max(biceps, back)))
                PrintLn("chest");
            if (biceps == Math.Max(chest, Math.Max(biceps, back)))
                PrintLn("biceps");
            if (back == Math.Max(chest, Math.Max(biceps, back)))
                PrintLn("back");

        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A.Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] x = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int chest = 0;
            int biceps = 0;
            int back = 0;
            for(int i=0;i<n;i+=3)
            {
                chest += x[i];
            } for (int i = 1; i < n; i += 3)
            {
                biceps += x[i];
            }
            for (int i = 2; i < n; i += 3)
            {
                back += x[i];
            }
            List<int> li = new List<int>();
            li.Add(chest); li.Add(biceps); li.Add(back);
            li.Sort();
            if(li[2]==chest)
            {
                Console.WriteLine("chest");
            }
            else if (li[2] == back)
            {
                Console.WriteLine("back");
            }
            else if (li[2] == biceps)
            {
                Console.WriteLine("biceps");
            }
        }
    }
}

using System;
class Solution
{
    public static void Main(string[] args)
    {
        int n = Convert.ToInt32(Console.ReadLine());
        string[] inputs = Console.ReadLine().Split(' ');
        int[] array = Array.ConvertAll(inputs, Int32.Parse);
        int k = 0, chest = 0, biseps = 0, back = 0;
        for (int i = 0; i < n; i++)
        {
            k++;
            if (k == 1) chest = chest + array[i];
            if (k == 2) biseps = biseps + array[i];
            if (k == 3) { back = back + array[i]; k = 0; }
        }
        if (chest > biseps && chest > back) Console.WriteLine("chest");
        if (biseps > chest && biseps > back) Console.WriteLine("biceps");
        if (back > chest && back > biseps) Console.WriteLine("back");
    }
}

using System;
  class Program
    {
        static void Main(string[] args)
        {
            string[] input = Console.In.ReadToEnd().Split(new char[] { ' ', '\t', '\r', '\n' }, StringSplitOptions.RemoveEmptyEntries);
            int[] counters = new int[3];
            for(int i=1; i<input.Length; ++i)
              counters[i%3]+=int.Parse(input[i]);
            input = null;
            int maxInd = 0;
            for(int i=1, curr = counters[0]; i<counters.Length; ++i)
             if (curr < counters[i]) { maxInd = i; curr = counters[i]; }
            counters = null;
            Console.WriteLine(maxInd == 0 ? "back" : maxInd == 1 ? "chest" : "biceps");
        }
    }

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;

namespace ConsoleApplication25
{
    class Program
    {
        static void Main(string[] args)
        {
            var init = int.Parse(Console.ReadLine());
            var nums = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

            int chest = 0;
            int bicepc = 0;
            int back = 0;

            for (int i = 0; i < init; i++)
            {
                if (i % 3 == 0)
                {
                    chest += nums[i];
                }
                else if (i % 3 == 1)
                {
                    bicepc += nums[i];
                }
                else
                {
                    back += nums[i];
                }
            }

           if (chest > bicepc && chest > back)
           {
               Console.WriteLine("chest");
           }
           else if (bicepc > chest && bicepc > back)
           {
               Console.WriteLine("biceps");
           }
           else
           {
               Console.WriteLine("back");
           }
                Console.ReadLine();
        }
    }
}

using System;
using System.Linq;

class A255 {
    static string[] Name = {"chest", "biceps", "back"};

    public static void Main() {
        var n = int.Parse(Console.ReadLine());
        var a = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
        var b = new int[3];
        int k = 0;
        for (int i = 0; i < n; ++i) {
            b[k] += a[i];
            k = k == 2 ? 0 : k + 1;
        }
        Console.WriteLine(Name[Array.IndexOf(b, b.Max())]);
    }
}

using System;
using System.Linq;

namespace AcmSolution
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Console.ReadLine();
            var s = Console.ReadLine().Split(' ');

            var a = new int[3];
            for (int i = 0; i < s.Length; ++i)
                a[i % 3] += int.Parse(s[i]);

            var max = a.Max();

            Console.WriteLine(a[0] == max ? "chest" : a[1] == max ? "biceps" : "back");
            Console.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Pr1
{
    class Program
    {
        static void Main()
        {
            int n=Convert.ToInt32(Console.ReadLine());
            var all= Array.ConvertAll(Console.ReadLine().Split(' '), Convert.ToInt32);
            int[] a=new int[3];
            int s=0;
            for(int i=1;i<=n;i++)
            {
                if((i+2)%3==0)
                    a[0]+=all[i-1];
                else if((i+1)%3==0)
                    a[1]+=all[i-1];
                else
                    a[2]+=all[i-1];
            }
            int max=a.Max();
            if(a[0]==max)
                Console.WriteLine("chest");
            else if(a[1]==max)
                 Console.WriteLine("biceps");
            else
                 Console.WriteLine("back");

        }
    }
}

using System;
using System.Linq;

class Program {
  static void Main() {
    Console.ReadLine();
    var a = Console.ReadLine().Split(' ').Select(int.Parse).Select((x, i) => new {x, Index = i % 3}).GroupBy(t => t.Index).OrderByDescending(g => g.Sum(g1 => g1.x)).First().Key;
    Console.Write((new [] {"chest", "biceps", "back"})[a]);
  }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CSharp_Contests
{
    public class Program
    {
        public static void Main() {
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split(new char[1] { ' ' }).Select(b => int.Parse(b)).ToArray();
            int c = 0, bi = 0, ba = 0;
            n = n - ( n % 3 );
            for (int i = 0; i < n; i += 3)
            {
                c += a[i];
                bi += a[i + 1];
                ba += a[i + 2];
            }
            if (a.Length - n > 0)
                c += a[n];
            if (a.Length - n > 1)
                bi += a[n + 1];
            if (a.Length - n > 2)
                c += a[n + 2];

            if (c > bi && c > ba)
                Console.WriteLine("chest");
            else if (bi > c && bi > ba)
                Console.WriteLine("biceps");
            else if (ba > c && ba > bi)
                Console.WriteLine("back");
#if DEBUG
            Console.ReadLine();
#endif
//ssss
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CSharp_Contests
{
    public class Program
    {
        public static void Main() {
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split(new char[1] { ' ' }).Select(b => int.Parse(b)).ToArray();
            int c = 0, bi = 0, ba = 0;
            n = n - ( n % 3 );
            for (int i = 0; i < n; i += 3)
            {
                c += a[i];
                bi += a[i + 1];
                ba += a[i + 2];
            }
            if (a.Length - n > 0)
                c += a[n];
            if (a.Length - n > 1)
                bi += a[n + 1];
            if (a.Length - n > 2)
                c += a[n + 2];

            if (c > bi && c > ba)
                Console.WriteLine("chest");
            else if (bi > c && bi > ba)
                Console.WriteLine("biceps");
            else if (ba > c && ba > bi)
                Console.WriteLine("back");
#if DEBUG
            Console.ReadLine();
#endif
        }
    }
}

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string[] c = Console.ReadLine().Split(' ');
            int iter = 0;
            int[] mass;
            mass = new int[3];
            for (int i = 0; i < n; i++)
            {
                int k = int.Parse(c[i]);
                mass[i % 3]+=k;
            }
            if (mass[0] > mass[1] && mass[0] > mass[2])
                Console.Write("chest");
            if (mass[1] > mass[0] && mass[1] > mass[2])
                Console.Write("biceps");
            if (mass[2] > mass[1] && mass[2] > mass[0])
                Console.Write("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A.Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            string[] s = Console.ReadLine().Split();
            int[] arr = new int[n];
            for(int i=0 ;i<n;i++)
            {
                arr[i] = int.Parse(s[i]);
            }
            int chestsum = 0;
            int bicepssum = 0;
            int backsum = 0;
            for(int i=0;i<n;i+=3)
            {
                chestsum += arr[i];
            }
            for (int i = 1; i < n; i += 3)
            {
                bicepssum += arr[i];
            }
            for (int i = 2; i < n; i += 3)
            {
                backsum += arr[i];
            }
            if(chestsum>bicepssum&&bicepssum>backsum)
            {
                Console.WriteLine("chest");
            }
            else if(chestsum>backsum&&backsum>bicepssum)
            {
                Console.WriteLine("chest");
            }
            else if (chestsum > backsum && backsum == bicepssum)
            {
                Console.WriteLine("chest");
            }
            else if (bicepssum > backsum && backsum > chestsum)
            {
                Console.WriteLine("biceps");
            }
            else if (bicepssum > chestsum && chestsum > backsum)
            {
                Console.WriteLine("biceps");
            }
            else if (bicepssum > chestsum && chestsum == backsum)
            {
                Console.WriteLine("biceps");
            }
            else if (backsum > chestsum && chestsum > bicepssum)
            {
                Console.WriteLine("back");
            }
            else if (backsum > bicepssum && bicepssum > chestsum)
            {
                Console.WriteLine("back");
            }
            else if (backsum > bicepssum && bicepssum == chestsum)
            {
                Console.WriteLine("back");
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Tar
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Util.getNum();
            int[] array = Util.getArray();

            int a =0;
            int b =0;
            int c = 0;
            for (int i = 0; i < array.Length;i++ )
            {
                if(i%3==0){
                    a += array[i];
                }

                if (i % 3 == 1)
                {
                    b += array[i];
                }

                if (i % 3 == 2)
                {
                    c += array[i];
                }
            }

            if(a>b && a>c){
                Console.WriteLine("chest");
            }

            if (b > a && b > c)
            {
                Console.WriteLine("biceps");
            }

            if (c > a && c > b)
            {
                Console.WriteLine("back");
            }
        }

        public static int exper(decimal p1, decimal p2){
            int res = 0;
            while(res == 0){

                Random random = new Random();
                if ((decimal)random.NextDouble() > p1)
                {
                    res = 1;
                }

                if ((decimal)random.NextDouble() > p2)
                {
                    res = -1;
                }
            }

            return res;
        }
    }

    class Util
    {
        public static int getNum()
        {
            return int.Parse(Console.ReadLine());
        }

        public static int[] getArray()
        {
            string[] str = Console.ReadLine().Split(' ');
            int[] array = new int[str.Length];

            for (int i = 0; i < array.Length; i++)
            {
                try
                {
                    array[i] = int.Parse(str[i]);
                }
                catch (Exception e)
                {
                    //Console.WriteLine(str[i]+"/");
                }
            }

            return array;
        }
    }
}

using System;
using System.IO;
using System.Linq;

class Program
{
    static char[] SPACE = new[] { ' ' };

    static void Main(string[] args)
    {
#if DEBUG
        using (var input = new StreamReader("input.txt"))
        using (var output = new StreamWriter("output.txt"))
        {
            Console.SetIn(input);
            Console.SetOut(output);

            int n = 0;
            do
            {
                Console.WriteLine();
                Console.WriteLine("Sample {0}", ++n);
                Prog();
            } while (Console.ReadLine() == string.Empty);
        }
#else
            Prog();
#endif
    }

    static int __ptr = 0;
    static string[] __input;
    static int NextInt()
    {
        return int.Parse(__input[__ptr++]);
    }
    static long NextLong()
    {
        return long.Parse(__input[__ptr++]);
    }
    static void ReadTokens(int n)
    {
        __ptr = 0;
        __input = Console.ReadLine().Split(SPACE, n);
    }

    //

    static void Prog()
    {
        ReadTokens(1);
        int n = NextInt();

        int[] r = new int[3];

        ReadTokens(n);
        for (int i = 0; i < n; i++)
            r[i % 3] += NextInt();

        int max = Math.Max(Math.Max(r[0], r[1]), r[2]);
        if (max == r[0]) Console.WriteLine("chest");
        else if (max == r[1]) Console.WriteLine("biceps");
        else if (max == r[2]) Console.WriteLine("back");
    }

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication3
{
    class Program
    {
        static int i(string s)
        {
            return Convert.ToInt32(s);
        }
        static void Main(string[] args)
        {
            int n = i(Console.ReadLine());
            int[] counts = new int[3];
            string[] s = Console.ReadLine().Split(' ');
            int j = 0;
            foreach (string s1 in s)
            {
                int temp = i(s1);
                counts[(j % 3)] += temp;
                j++;
            }
            int argmax = 0;
            int max = -1;
            for (int k = 0; k < 3; k++)
            {
                if (max < counts[k])
                {
                    max = counts[k];
                    argmax = k;
                }
            }
            if(argmax == 0)
                Console.WriteLine("chest");
            else if(argmax == 1)
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");

        }
    }
}

using System;
using System.IO;
using System.Text;

namespace Greg_s_Workout
{
    internal class Program
    {
        private static readonly StreamReader reader = new StreamReader(Console.OpenStandardInput(1024*10), Encoding.ASCII, false, 1024*10);
        private static readonly StreamWriter writer = new StreamWriter(Console.OpenStandardOutput(1024*10), Encoding.ASCII, 1024*10);

        private static void Main(string[] args)
        {
            int n = Next();

            var nn = new int[3];
            for (int i = 0; i < n; i++)
            {
                nn[i%3] += Next();
            }

            if (nn[0] > nn[1] && nn[0] > nn[2])
                writer.WriteLine("chest");
            else if (nn[1] > nn[2] && nn[1] > nn[2])
                writer.WriteLine("biceps");
            else
            {
                writer.WriteLine("back");
            }

            writer.Flush();
        }

        private static int Next()
        {
            int c;
            int res = 0;
            do
            {
                c = reader.Read();
                if (c == -1)
                    return res;
            } while (c < '0' || c > '9');
            res = c - '0';
            while (true)
            {
                c = reader.Read();
                if (c < '0' || c > '9')
                    return res;
                res *= 10;
                res += c - '0';
            }
        }
    }
}

using System;

namespace ConsoleApplication1
{
    internal class Program
    {
        private static int n;
        private static string[] s;
        private static int[] a;
        private static int x = 0, y = 0, z = 0;

        private static void Main(string[] args)
        {
            n = int.Parse(Console.ReadLine());

            s = Console.ReadLine().Split(' ');

            var k = 1;

            for (int i = 0; i < n; i++)
            {
                switch (k)
                {
                    case 1 :
                        x += int.Parse(s[i]);
                        break;
                    case 2:
                        y += int.Parse(s[i]);
                        break;
                    case 3:
                        z += int.Parse(s[i]);
                        break;
                }

                if (k == 3)
                    k = 1;
                else
                    k++;
            }

            Console.WriteLine(x > y ? x > z ? "chest" : "back" : y > z ? "biceps" : "back");
        }
    }
}

using System;
using System.Linq;

namespace egor
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] exercises = { 0, 0, 0 };
            char c;
            int count = int.Parse(Console.ReadLine());

            for (int i = 0; i < count; i++)
            {
                string tmp = "";
                while (char.IsDigit(c = (char)(Console.Read()))) tmp += c;
                exercises[i % 3] += Convert.ToInt32(tmp);
            }

            switch (exercises.ToList().IndexOf(exercises.Max()))
            {
                case 0:
                    Console.WriteLine("chest");
                    break;

                case 1:
                    Console.WriteLine("biceps");
                    break;

                case 2:
                    Console.WriteLine("back");
                    break;
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;
using System.IO;
using System.Numerics;
using System.Globalization;
using System.Threading;

namespace probleme {
    class Program {
        static void Main(string[] args) {
            //Console.SetIn(new StreamReader("file.txt"));
            int n = int.Parse(Console.ReadLine());
            int[] a = Array.ConvertAll(Console.ReadLine().Split(' '), tz => int.Parse(tz));
            int na = 0, nb = 0, nc = 0;
            for (int i = 0; i < n; i++) {
                if (i % 3 == 0)
                    na += a[i];
                else if (i % 3 == 1)
                    nb += a[i];
                else
                    nc += a[i];
            }
            if (na > nb && na > nc)
                Console.WriteLine("chest");
            else if (nb > na && nb > nc)
                Console.WriteLine("biceps");
            else
                Console.WriteLine("back");
            //Console.ReadKey();
        }
    }
}

using System;
using System.Globalization;
using System.IO;
using System.Linq;

namespace CF317
{
	internal class Program
	{
		private static void Main(string[] args)
		{
			var sr = new InputReader(Console.In);
			//var sr = new InputReader(new StreamReader("input.txt"));
			var task = new Task();
			using (var sw = Console.Out)
				//using (var sw = new StreamWriter("output.txt"))
			{
				task.Solve(sr, sw);
				//Console.ReadKey();
			}
		}
	}

	internal class Task
	{
		public void Solve(InputReader sr, TextWriter sw)
		{
			var n = sr.NextInt32();
			var array = sr.ReadArray(Int32.Parse);
			var firstCount = 0;
			var secondcount = 0;
			var thirdCount = 0;
			for (var i = 0; i < n; i++) {
				if (i % 3 == 0) {
					firstCount += array[i];
				}
				if (i % 3 == 1) {
					secondcount += array[i];
				}
				if (i % 3 == 2) {
					thirdCount += array[i];
				}
			}

			var max = Math.Max(firstCount, Math.Max(secondcount, thirdCount));
			if (max == firstCount) {
				sw.WriteLine("chest");
			}
			else {
				if (max == secondcount) {
					sw.WriteLine("biceps");
				}
				else {
					sw.WriteLine("back");
				}
			}
		}
	}
}

internal class InputReader : IDisposable
{
	private bool isDispose;
	private readonly TextReader sr;

	public InputReader(TextReader stream)
	{
		sr = stream;
	}

	public void Dispose()
	{
		Dispose(true);
		GC.SuppressFinalize(this);
	}

	public string NextString()
	{
		var result = sr.ReadLine();
		return result;
	}

	public int NextInt32()
	{
		return Int32.Parse(NextString());
	}

	public long NextInt64()
	{
		return Int64.Parse(NextString());
	}

	public string[] NextSplitStrings()
	{
		return NextString()
			.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
	}

	public T[] ReadArray<T>(Func<string, CultureInfo, T> func)
	{
		return NextSplitStrings()
			.Select(s => func(s, CultureInfo.InvariantCulture))
			.ToArray();
	}

	public T[] ReadArrayFromString<T>(Func<string, CultureInfo, T> func, string str)
	{
		return
			str.Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries)
				.Select(s => func(s, CultureInfo.InvariantCulture))
				.ToArray();
	}

	protected void Dispose(bool dispose)
	{
		if (!isDispose) {
			if (dispose)
				sr.Close();
			isDispose = true;
		}
	}

	~InputReader()
	{
		Dispose(false);
	}
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CF_GregWorkout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] a = Array.ConvertAll(Console.ReadLine().Split(' '), int.Parse);
            Dictionary<string, int> dict = new Dictionary<string, int>();
            dict.Add("chest", 0);
            dict.Add("biceps", 0);
            dict.Add("back", 0);
            for(int i=0;i<n;i++)
            {
                if(i % 3 == 0)
                {
                    dict["chest"] = dict["chest"] + a[i];
                }
                else if (i % 3 == 1)
                {
                    dict["biceps"] = dict["biceps"] + a[i];
                }
                else if (i % 3 == 2)
                {
                    dict["back"] = dict["back"] + a[i];
                }
            }
            int max = dict.Values.Max();
            Console.WriteLine(dict.Single(d => d.Value == max).Key);
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;

namespace prA {

    class Program {
#if ONLINE_JUDGE
        private static readonly StreamReader reader = new StreamReader(Console.OpenStandardInput(1024 * 10), System.Text.Encoding.ASCII, false, 1024 * 10);
        private static readonly StreamWriter writer = new StreamWriter(Console.OpenStandardOutput(1024 * 10), System.Text.Encoding.ASCII, 1024 * 10);
#else
        private static readonly StreamWriter writer = new StreamWriter("output");
        private static readonly StreamReader reader = new StreamReader("input");
#endif
        static void Main(string[] args) {
            string[] w = {"chest", "biceps", "back"};
            int n = Next();
            int[] q = new int[3];
            int p = 0;
            int maxi = 0;
            for(int i = 0; i < n; i++) {
                int a = Next();
                q[p] += a;
                if(q[p] > q[maxi])
                    maxi = p;
                ++p;
                p %= 3;
            }
            writer.WriteLine(w[maxi]);
            writer.Flush();
#if !ONLINE_JUDGE
            writer.Close();
#endif
        }
        private static int Next() {
            int c;
            int res = 0;
            do {
                c = reader.Read();
                if(c == -1)
                    return res;
            } while(c != '-' && (c < '0' || c > '9'));
            int sign = 1;
            if(c == '-') {
                sign = -1;
                c = reader.Read();
            }
            res = c - '0';
            while(true) {
                c = reader.Read();
                if(c < '0' || c > '9')
                    return res * sign;
                res *= 10;
                res += c - '0';
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Text.RegularExpressions;

class ans:IComparable<ans>
{
    public int a;
    public string name;
    public ans(int a, string s)
    {
        this.a = a;
        name = s;
    }
    public int CompareTo(ans a)
    {
        return this.a.CompareTo(a.a);
    }

}
class PairVariable:IComparable<PairVariable>
{
    public int a, b;
    public PairVariable()
    {
        a = b = 0;
    }
    public PairVariable(string s)
    {
        string[] q = s.Split();
        a = int.Parse(q[0]);
        b = int.Parse(q[1]);
    }
    public PairVariable(int a, int b)
    {
        this.a = a;
        this.b = b;
    }
    public int CompareTo(PairVariable pv)
    {
        if (this.a > pv.a)
        {
            return 1;
        }
        else if (this.a < pv.a)
        {
            return -1;
        }
        else
        {
            if (this.b >= pv.b)
            {
                return 1;
            }
            else
            {
                return -1;
            }
        }
    }

}
namespace ConsoleApplication252
{

    class Program
    {

        static bool P(int n)
        {
            for (int i = 2; i <= Math.Sqrt(n); i++)
            {
                if (n % i == 0)
                {
                    return false;
                }
            }
            return true;
        }

        static void Main()
        {
            int n = int.Parse(Console.ReadLine());
            string[] ss = Console.ReadLine().Split();
            int[] m = new int[n + 1];
            for (int i = 1; i < n + 1; i++)
            {
                m[i] = int.Parse(ss[i-1]);
            }
            int chest = 0;
            int biceps = 0;
            int back = 0;
            for (int i = 1; i < m.Length; i++)
            {
                if (i % 3 == 0)
                {
                    back += m[i];
                }
                else if (i % 3 == 1)
                {
                    chest += m[i];
                }
                else
                {
                    biceps += m[i];
                }

            }
            ans[] an = new ans[3];
            an[0] = new ans(chest, "chest");
            an[1] = new ans(biceps, "biceps");
            an[2] = new ans(back, "back");
            Array.Sort(an);
            Console.WriteLine(an[2].name);

        }
    }
}

using System;
using System.Linq;
using System.Collections.Generic;

namespace tren
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine()), chest = 0, biceps = 0, back = 0;
            List<int> mass = Console.ReadLine().Split(' ').Select(int.Parse).ToList();
            for (int i = 0; i < n; i++)
            {
                if (i % 3 == 0)
                {
                    chest += mass[i];
                    mass[i] = 0;
                }
            }
            for (int i = 0; i < mass.Count(); i++)
            {
                if (mass[i] == 0) mass.Remove(mass[i]);
            }

            for (int i = 0; i < mass.Count(); i++)
            {
                if (i % 2 == 0) biceps += mass[i];
                else back += mass[i];
            }
            if (biceps > chest && biceps > back) Console.Write("biceps");
            if (chest  > biceps && chest > back) Console.Write("chest");
            if (back > chest && back > biceps) Console.Write("back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ASM
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Int32.Parse(Console.ReadLine());
            int[] workout = Console.ReadLine().Split(' ').Select(x => Int32.Parse(x)).ToArray<int>();
            int chest = 0;
            int biceps = 0;
            int back = 0;

            for(int i = 0; i < n / 3; i++)
            {
                chest += workout[i*3];
                biceps += workout[i*3+1];
                back += workout[i*3+2];
            }

            if(n % 3 == 1)
                chest += workout[n - 1];
            else if(n%3 == 2)
            {
                chest += workout[n - 2];
                biceps += workout[n - 1];
            }

            if(chest > biceps && chest > back)
                Console.WriteLine("chest");
            else if (biceps > chest && biceps > back)
                Console.WriteLine("biceps");
            else if (back > chest && back > biceps)
                Console.WriteLine("back");
        }

    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A.Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int Number = int.Parse(Console.ReadLine());
            string[] Exe = (Console.ReadLine()).Split(' ');
            int chest = 0, biceps = 0, back = 0;
            bool Chest = true, Biceps = false, Back = false;
            for (int i = 0; i < Number; i++)
            {
                if (Chest)
                {
                    chest+=int.Parse(Exe[i]);
                    Chest = false;
                    Biceps = true;
                }
                else if (Biceps)
                {
                    biceps+= int.Parse(Exe[i]);
                    Biceps = false;
                    Back = true;
                }
                else
                {
                    back+= int.Parse(Exe[i]);
                    Chest = true;
                    Back = false;
                }

            }
            if (chest > biceps && chest > back)
            {
                Console.WriteLine("chest");
            }
            else if (biceps > chest && biceps > back)
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading.Tasks;

namespace fun
{
    class Program
    {
        private static TextReader cin = Console.In;
        private static TextWriter cout = Console.Out;
        static void Main(string[] args)
        {
            string s = cin.ReadLine() ;
            int n = int.Parse(s.Split(' ')[0]);
            var t = Array.ConvertAll(cin.ReadLine().Split(' '), int.Parse);
            int a = 0, b = 0, c = 0 ;

            for (int i = 0; i < n; i++)
            {
                if (i % 3 == 0) a += t[i];
                if (i % 3 == 1) b += t[i];
                if (i % 3 == 2) c += t[i];
            }
            int m =Math.Max(a, Math.Max(b, c));
            cout.Write((m == a) ? "chest" : ((m == b) ? "biceps" : "back"));
            //cin.ReadLine();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication1
{
    public class Program
    {
        public static void Main()
        {
            int days;
            int[] exercises;
            int[] type = new int[3];
            string[] body = { "chest", "biceps", "back" };

            days = Convert.ToInt32(Console.ReadLine());

            exercises = (Console.ReadLine().Split(' ')).Select(n => Convert.ToInt32(n)).ToArray();
            int j = 0;

            for (int i = 0; i < days; ++i)
            {
                type[j] += exercises[i];
                if (j == 2)
                    j = 0;
                else
                    ++j;
            }
            int Max = type.ToList().IndexOf(type.Max());

            Console.WriteLine(body[Max]);
        }
    }
}

using System;
using System.Linq;
class Program
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine());
        var a = Console.ReadLine().Split().Select(int.Parse).ToArray();
        var m = new int[3];
        for (int i = 0; i < n; i++)
        {
            m[i % 3] += a[i];
        }
        Console.WriteLine("{0}", new string[] { "chest", "biceps", "back" }[Array.IndexOf(m, m.Max())]);
    }
}

using System;

namespace AllProblems
{
    class Program
    {
        static void Main(string[] args)
        {
            _255A_GregsWorkout.Run();

        }
    }
    class _255A_GregsWorkout
    {
        public static void Run()
        {
            var n = byte.Parse(Console.ReadLine().Trim());
            var l = Console.ReadLine().Trim().Split(' ');

            var len = n > 3 ? 3 : n;
            var arr = new short[len];
            var ind = new short[len];

            for (byte i = 0; i < len; i++)
                ind[i] = i;

            for (byte i = 0; i < n; i++)
                arr[i%3] += byte.Parse(l[i]);

            Array.Sort(arr,ind);
            var m = new[] {"chest", "biceps", "back"};
            Console.WriteLine(m[ind[len - 1]]);
            Console.ReadLine();
        }
    }
}

using System;
using System.Linq;

namespace codeforces
{
    class Program
    {
        static void Main(string[] args)
        {
            int count = int.Parse(Console.ReadLine());
            int[] s = Console.ReadLine().Split().Select(int.Parse).ToArray();
            //int numbers = Console.ReadLine().Split().Count(x => x.Count(y => y == '4' || y == '7') <= s[1]);
            int chest=0, biceps=0, back=0;
            for (int i = 1; i <= count; i++)
            {
                if (i % 3 == 1)
                    chest += i * s[i-1];
                if (i % 3 == 2)
                    biceps += i * s[i-1];
                if (i % 3 == 0)
                    back += i * s[i-1];
            }

            Console.WriteLine(chest>biceps&&chest>back? "chest" : biceps>chest&&biceps>back? "biceps" : "back");

        }
    }
}

using System;
using static System.Console;
using System.Windows;
using static System.Math;

namespace ConsoleApp6
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(ReadLine());
            string[] b = ReadLine().Split(' ');
            int[] a = new int[b.Length + 1];
            int back = 0, biceps = 0, chest = 0;
            for (int i = 1; i <= b.Length; i++)
            {
                a[i] = Convert.ToInt32(b[i - 1]);
            }
            for (int i = 1; i <= b.Length; i++)
            {
                if (i % 3 == 0) back += a[i];
                else if (i % 2 == 0) biceps += a[i];
                else if (i % 2 == 1) chest += a[i];
            }
            if (Max(Max(back, biceps), chest) == back) WriteLine("back");
            else if (Max(Max(back, biceps), chest) == biceps) WriteLine("biceps");
            else Write("chest");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] y = Console.ReadLine().Split(' ');
            int[] a = new int[y.Length];
            for (int i = 0; i < a.Length; i++)
            {
                a[i] = int.Parse(y[i]);
            }
            int chest = 0;
            int biceps = 0;
            int back = 0;
            for (int i = 0; i < a.Length; i += 3)
            {
                if (i < a.Length)
                {
                    chest += a[i];
                }
            }
            for (int i = 1; i < a.Length; i += 3)
            {
                if (i < a.Length)
                {
                    biceps += a[i];
                }
            }
            for (int i = 2; i < a.Length; i += 3)
            {
                if (i < a.Length)
                {
                    back += a[i];
                }
            }
            if ((chest > back) && (chest > biceps))
            {
                Console.WriteLine("chest");

            }
            if ((back > biceps) && (back > chest))
            {
                Console.WriteLine("back");

            }
            if ((biceps > back) && (biceps > chest))
            {
                Console.WriteLine("biceps");

            }
                //Console.ReadKey();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace A.Greg_s_Workout
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int chest = 0, biceps = 0, back = 0;
            int[] arr = Console.ReadLine().Split().Select(int.Parse).ToArray();
            if (n > 3)
            {
                for (int i = 0; i < n; i += 3)
                {
                    chest += arr[i];
                }
                for (int i = 1; i < n; i += 3)
                {
                    biceps += arr[i];
                }
                for (int i = 2; i < n; i += 3)
                {
                    back += arr[i];
                }
            }
            else
            {
                if (n == 3)
                {
                    chest = arr[0];
                    biceps = arr[1];
                    back = arr[2];
                }
                if (n == 2)
                {
                    chest = arr[0];
                    biceps = arr[1];
                }
                else if (n == 1) Console.WriteLine("chest");
            }
            string[] s = { "chest", "biceps", "back" };
            int[] final = { chest, biceps, back };
            Console.WriteLine(s[Array.IndexOf(final, final.Max())]);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace CodeForces
{
    class Program_R156_Div2_A
    {
        static void Main(string[] args)
        {
            int n = Convert.ToInt32(Console.ReadLine());
            string[] s = (Console.ReadLine().Split());
            int[] b = new int[Math.Max(n,3)];
            for (int i = 0; i < n; i++)
                b[i] = Convert.ToInt32(s[i]);

            for (int j = 3; j < n; j++)
                b[j % 3] += b[j];

            string ans = "back";
            if (b[0] > b[1] && b[1] > b[2])
                ans = "chest";
            else if (b[1] > b[0] && b[1] > b[2])
                ans = "biceps";

            Console.WriteLine(ans);
        }
    }
}

using System;
using System.Text;

namespace pr111
{
    class Program
    {
        public static void Main(string[] args)
        { int a,b,c,n;string s;
            n=Convert.ToInt16(Console.ReadLine());
            int[] arr;
            arr= new int[24];
            a = 0; b =0; c =0;
            string[] line=Console.ReadLine().Split();
            for (int i=0; i<line.Length; i++) {arr[i]=Convert.ToInt16(line[i]);}
            for (int i=0; i<n-1; i+=3) {a+=arr[i]; b+=arr[i+1]; c+=arr[i+2];}
            if (a>=b&&a>=c) {s="chest";} else {if(b>c){s="biceps";} else {s="back";}}
            Console.WriteLine(Convert.ToString(s));
            //Console.ReadKey(true);
        }
    }
}

using System;

namespace ConsoleApplication32
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = Int32.Parse(Console.ReadLine());
            int[] a = new int[n];
            string str = Console.ReadLine();
            string[] subString = str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            int b = 0;
            int c = 0;
            int d = 0;
            for (int i = 0; i < n; i++)
            {
                a[i] = Convert.ToInt32(subString[i]);
            }
            for (int i = 0; i < n; i = i + 3)
            {
                b = b + a[i];
            }
            for (int i = 1; i < n; i = i + 3)
            {
                c = c + a[i];
            }
            for(int i = 2; i < n; i = i + 3)
            {
                d = d + a[i];
            }
            if (b > c && b > d)
            {
                Console.WriteLine("biceps");
            }
            else if (c > d)
            {
                Console.WriteLine("back");
            }
            else
            {
                Console.WriteLine("chest");
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _255A
{
    class Program
    {
        static void Main(string[] args)
        {
            int chest = 0, biceps = 0, back = 0;
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split().Select(_ => int.Parse(_)).ToArray();
            for(int i = 0;i<n;i++)
            {
                switch((i+1)%3)
                {
                    case 1:chest++;break;
                    case 2:biceps++;break;
                    case 0:back++;break;
                }
            }
            if (chest < biceps)
                Console.WriteLine(biceps > back ? "biceps" : "back");
            else
                Console.WriteLine(chest > back ? "chest" : "back");
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _255A
{
    class Program
    {
        static void Main(string[] args)
        {
            int chest = 0, biceps = 0, back = 0;
            int n = int.Parse(Console.ReadLine());
            int[] a = Console.ReadLine().Split().Select(_ => int.Parse(_)).ToArray();
            for(int i = 0;i<n;i++)
            {
                switch((i+1)%3)
                {
                    case 1:chest++;break;
                    case 2:biceps++;break;
                    case 3:back++;break;
                }
            }
            if (chest < biceps)
                Console.WriteLine(biceps > back ? "biceps" : "back");
            else
                Console.WriteLine(chest > back ? "chest" : "back");
        }
    }
}

using System;

namespace codeforces{
  public class task{
    static void Main(){
      int n;
      int []tr={0,0,0};
      n=Convert.ToInt32(Console.ReadLine());
      int []training=new int[n];
      string[] str = Console.ReadLine().Split(new char[] { ' ', '\n', '\t' }, StringSplitOptions.RemoveEmptyEntries);
      for(int i=0;i<n;i++){
        training[i]=Convert.ToInt32(str[i]);
      }
      for(int i=0,k=1;i<n;i++,k++){
        if(k==1){
          tr[0]+=training[i];
        }else{
          if(k==2){
            tr[1]+=training[i];
          }else if(k==3){
            tr[2]+=training[i];
            k=1;
          }
        }
      }
      if(tr[0]>tr[1]&&tr[0]>tr[2]){
        Console.WriteLine("chest");
      }else{
        if(tr[1]>tr[0]&&tr[1]>tr[2]){
          Console.WriteLine("biceps");
        }else{
          Console.WriteLine("back");
        }
      }
    }
  }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp10
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int[] y = new int[3];
            for (int i = 0; i < n; i++)
            {
                if ((i+1)%3==1)
                {
                    y[1]++;
                    continue;
                }
                else if ((i+1%3)==2)
                {
                    y[2]++;
                }
                else
                {
                    y[0]++;
                }
            }
            if (y.Max() == y[0])
            {
                Console.WriteLine("chest");
            }
            else if (y.Max() ==y[1])
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp10
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int u = 0;
            int y = 0;
            for (int i = 1; i < n; i++)
            {
                if (l[i]>l[i-1])
                {
                    u = l[i];
                    y = i;
                }
            }
            if ((y+1)%3==1)
            {
                Console.WriteLine("chest");
            }
             else if((y+1)%3==2)
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp10
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int[] y = new int[3];
            for (int i = 0; i < n; i++)
            {
                if ((i+1)%3==1)
                {
                    y[0]+=l[i];
                    continue;
                }
                else if ((i+1%3)==2)
                {
                    y[1]+=l[i];
                    continue;
                }
                else
                {
                    y[2]+=l[i];
                }
            }
            if (y.Max() == y[0])
            {
                Console.WriteLine("chest");
            }
            else if (y.Max() ==y[1])
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp10
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int[] y = new int[3];
            for (int i = 0; i < n; i++)
            {
                if ((i+1)%3==1)
                {
                    y[1]++;
                    continue;
                }
                else if ((i+1%3)==2)
                {
                    y[2]++;
                }
                else
                {
                    y[0]++;
                }
            }
            if (l.Max() == y[0])
            {
                Console.WriteLine("chest");
            }
            else if (l.Max() ==y[1])
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }

        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp10
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] l = Console.ReadLine().Split().Select(int.Parse).ToArray();
            int[] y = new int[3];
            for (int i = 0; i < n; i++)
            {
                if ((i+1)%3==1)
                {
                    y[1]++;
                    continue;
                }
                else if ((i+1%3)==2)
                {
                    y[2]++;
                }
                else
                {
                    y[0]++;
                }
            }
            if (l.Max() == l[0])
            {
                Console.WriteLine("chest");
            }
            else if (l.Max() ==l[1])
            {
                Console.WriteLine("biceps");
            }
            else
            {
                Console.WriteLine("back");
            }

        }
    }
}

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;

namespace ConsoleApplication25
{
    class Program
    {
        static void Main(string[] args)
        {
            var init = int.Parse(Console.ReadLine());
            var nums = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

            int chest = 0;
            int bicepc = 0;
            int back = 0;

            for (int i = 1; i <= init; i++)
            {
                if (i % 3 == 0)
                {
                    back += nums[i-1];
                }
                else if (i % 3 != 0 && i % 2 == 0)
                {
                    bicepc += nums[i-1];
                }
                else
                {
                    chest += nums[i-1];
                }
            }

           if (chest > bicepc && chest > back)
           {
               Console.WriteLine("chest");
           }
           else if (bicepc > chest && bicepc > back)
           {
               Console.WriteLine("biceps");
           }
           else
           {
               Console.WriteLine("back");
           }
                Console.ReadLine();
        }
    }
}

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Globalization;

namespace ConsoleApplication25
{
    class Program
    {
        static void Main(string[] args)
        {
            var init = int.Parse(Console.ReadLine());
            var nums = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();

            int chest = 0;
            int bicepc = 0;
            int back = 0;

            for (int i = 0; i < init; i++)
            {
                if (nums[i] % 3 == 0)
                {
                    chest += nums[i];
                }
                else if (nums[i] % 3 != 0 && nums[i] % 2 == 0)
                {
                    bicepc += nums[i];
                }
                else
                {
                    back += nums[i];
                }
            }

           if (chest > bicepc && chest > back)
           {
               Console.WriteLine("chest");
           }
           else if (bicepc > chest && bicepc > back)
           {
               Console.WriteLine("biceps");
           }
           else
           {
               Console.WriteLine("back");
           }
                Console.ReadLine();
        }
    }
}

using System;
using System.Linq;

class Program {
  static void Main() {
    Console.ReadLine();
    var a = Console.ReadLine().Split(' ').Select(int.Parse).Select((x, i) => new {x, Index = i % 3}).GroupBy(t => t.Index).OrderByDescending(g => g.Count()).First().Key;
    Console.Write((new [] {"chest", "biceps", "back"})[a]);
  }
}

using System;
using System.Linq;

class Program {
  static void Main() {
    Console.ReadLine();
    var a = Console.ReadLine().Split(' ').Select(int.Parse).Select((i, x) => i % 3).GroupBy(t => t).OrderByDescending(g => g.Count()).First().Key;
    Console.Write((new [] {"chest", "biceps", "back"})[a]);
  }
}

using System;

namespace ConsoleApplication1
{
    internal class Program
    {
        private static int n;
        private static string[] s;
        private static int[] a;
        private static int x = 0, y = 0, z = 0;

        private static void Main(string[] args)
        {
            n = int.Parse(Console.ReadLine());

            s = Console.ReadLine().Split(' ');

            var k = 1;

            for (int i = 0; i < n; i++)
            {
                switch (k)
                {
                    case 1 :
                        x += int.Parse(s[i]);
                        break;
                    case 2:
                        y += int.Parse(s[i]);
                        break;
                    case 3:
                        z += int.Parse(s[i]);
                        break;
                }

                if (k == 3)
                    k = 0;
                else
                    k++;
            }

            Console.WriteLine(x > y ? x > z ? "chest" : "back" : y > z ? "biceps" : "back");
        }
    }
}

using System;
using System.Linq;
using System.Collections.Generic;

namespace tren
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine()), chest = 0, biceps = 0, back = 0;
            List<int> mass = Console.ReadLine().Split(' ').Select(int.Parse).ToList();
            chest = mass.Where(x => mass.IndexOf(x) % 3 == 0).Sum();
            for (int i = 0; i < n; i++)
            {
                if (i % 3 == 0) mass[i] = 0;
            }
            for (int i = 0; i < mass.Count(); i++)
            {
                if (mass[i] == 0) mass.Remove(mass[i]);
            }

            for (int i = 0; i < mass.Count(); i++)
            {
                if (i % 2 == 0) biceps += mass[i];
                else back += mass[i];
            }
            if (biceps > chest && biceps > back) Console.Write("biceps");
            if (chest  > biceps && chest > back) Console.Write("chest");
            if (back > chest && back > biceps) Console.Write("back");
        }
    }
}

using System;
using System.Linq;
class Program
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine());
        var a = Console.ReadLine().Split().Select(int.Parse).ToArray();
        var m = new int[3];
        for (int i = 0; i < n; i++)
        {
            m[i % 3]++;
        }
        Console.WriteLine("{0}", new string[] { "chest", "biceps", "back" }[Array.IndexOf(m, m.Max())]);
    }
}

using System;
using System.Linq;
class Program
{
    static void Main()
    {
        var n = int.Parse(Console.ReadLine());
        var a = Console.ReadLine().Split().Select(int.Parse).ToArray();
        var muscle = new int[3];
        for (int i = 0; i < n; i++)
        {
            muscle[i % 3]++;
        }
        Console.WriteLine(muscle[0] > muscle[1] ? "chest" : muscle[1] > muscle[2] ? "biceps" : "back");
    }
}