A way to make a new task is to make it nondeterministic or probabilistic. For example, the hard task of Topcoder SRM 595, Constellation, is the probabilistic version of a convex hull.Let's try to make a new task. Firstly we will use the following task. There are n people, sort them by their name. It is just an ordinary sorting problem, but we can make it more interesting by adding nondeterministic element. There are n people, each person will use either his/her first name or last name as a handle. Can the lexicographical order of the handles be exactly equal to the given permutation p?More formally, if we denote the handle of the i-th person as hi, then the following condition must hold: .

The first line contains an integer n (1 ≤ n ≤ 105) — the number of people. The next n lines each contains two strings. The i-th line contains strings fi and si (1 ≤ |fi|, |si| ≤ 50) — the first name and last name of the i-th person. Each string consists only of lowercase English letters. All of the given 2n strings will be distinct. The next line contains n distinct integers: p1, p2, ..., pn (1 ≤ pi ≤ n).

If it is possible, output "YES", otherwise output "NO".

3
gennady korotkevich
petr mitrichev
gaoyuan chen
1 2 3

3
gennady korotkevich
petr mitrichev
gaoyuan chen
3 1 2

2
galileo galilei
nicolaus copernicus
2 1

10
rean schwarzer
fei claussell
alisa reinford
eliot craig
laura arseid
jusis albarea
machias regnitz
sara valestin
emma millstein
gaius worzel
1 2 3 4 5 6 7 8 9 10

10
rean schwarzer
fei claussell
alisa reinford
eliot craig
laura arseid
jusis albarea
machias regnitz
sara valestin
emma millstein
gaius worzel
2 4 9 6 5 7 1 3 8 10

NoteIn example 1 and 2, we have 3 people: tourist, Petr and me (cgy4ever). You can see that whatever handle is chosen, I must be the first, then tourist and Petr must be the last.In example 3, if Copernicus uses "copernicus" as his handle, everything will be alright.

package main

import (
	"bufio"
	"fmt"
	"os"
)

var in = bufio.NewScanner(os.Stdin)

func readInt() int {
	if !in.Scan() {
		panic(in.Err())
	}
	res := 0
	for _, b := range in.Bytes() {
		res = res*10 + int(b-'0')
	}
	return res
}

func readString() string {
	if !in.Scan() {
		panic(in.Err())
	}
	return in.Text()
}

func main() {
	in.Split(bufio.ScanWords)
	n := readInt()
	f := make([]string, n)
	s := make([]string, n)
	for i := range f {
		f[i] = readString()
		s[i] = readString()
	}
	p := make([]int, n)
	for i := range p {
		p[i] = readInt() - 1
	}
	canF, canS := true, true
	for i := 1; i < n; i++ {
		canF, canS = canF && f[p[i-1]] < f[p[i]] || canS && s[p[i-1]] < f[p[i]], canF && f[p[i-1]] < s[p[i]] || canS && s[p[i-1]] < s[p[i]]
	}
	if canF || canS {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}

package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
	"strconv"
)

func main() {
	var n int
	var line string

	reader := bufio.NewReader(os.Stdin)

	line, _ = reader.ReadString('\n')
	n, _ = strconv.Atoi(strings.TrimSpace(line))
	names := make([][2]string, n)
	for i := 0; i < n; i++ {
		line, _ = reader.ReadString('\n')
		line = strings.TrimSpace(line)
		nicks := strings.Split(line, " ")
		if nicks[0] < nicks[1] {
			names[i][0] = nicks[0]
			names[i][1] = nicks[1]
		} else {
			names[i][1] = nicks[0]
			names[i][0] = nicks[1]
		}
	}

	line, _ = reader.ReadString('\n')
	line = strings.TrimSpace(line)
	s_permutation := strings.Split(line, " ")
	permutation := make([]int, n)
	for i := 0; i < n; i++ {
		permutation[i], _ = strconv.Atoi(s_permutation[i])
		permutation[i]--
	}

	last := ""
	for i := 0; i < n; i++ {
		if last < names[permutation[i]][0] {
			last = names[permutation[i]][0]
		} else if last < names[permutation[i]][1] {
			last = names[permutation[i]][1]
		} else {
			fmt.Println("NO")
			return
		}
	}
	fmt.Println("YES")
}

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)
var writer = bufio.NewWriter(os.Stdout)

type Name struct {
	first, last string
	p int
}

//Wrong
func main() {
	defer writer.Flush()
	scanner.Split(bufio.ScanWords)

	n := nextInt()
	names := make([]Name, n)

	if n == 1 {
		println("YES")
		return
	}

	for i := 0; i < n; i++ {
		names[i].first = next()
		names[i].last = next()
	}

	for i := 0; i < n; i++ {
		names[i].p = nextInt() - 1
	}

	p := names[0].p
	var lastHandle *string

	if names[p].first < names[p].last {
		lastHandle = &names[p].first
	} else	 {
		lastHandle = &names[p].last
	}

	for i := 1; i < n; i++ {
		p = names[i].p

		switch {
		case *lastHandle < names[p].first && *lastHandle < names[p].last:
			if names[p].first < names[p].last {
				lastHandle = &names[p].first
			} else {
				lastHandle = &names[p].last
			}
		case *lastHandle < names[p].first:
			lastHandle = &names[p].first
		case *lastHandle < names[p].last:
			lastHandle = & names[p].last
		default:
			println("NO")
			return
		}
	}

	println("YES")

	// p := names[0].p

	// if isLexico(1, &names[p].first, names) || isLexico(1, &names[p].last, names) {
	// 	println("YES")
	// } else {
	// 	println("NO")
	// }

	// println(names)
}

func isLexico(i int, handle *string, names []Name) bool {
	if i == len(names) {
		return true
	}

	for ; i < len(names); i++ {
		p := names[i].p
			// println(handle, i, names[p])
		switch {
		case *handle < names[p].first && *handle < names[p].last:
			return isLexico(i+1, &names[p].first, names) || isLexico(i+1, &names[p].last, names)
		case *handle < names[p].first:
			*handle = names[p].first
		case *handle < names[p].last:
			*handle = names[p].last
		default:
			return false
		}
	}

	return true
}

func next() string {
	if !scanner.Scan() {
		panic("Scan error")
	}
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(next())
	if err != nil {
		panic(err)
	}
	return n
}

func nextFloat() float64 {
	n, err := strconv.ParseFloat(next(), 64)
	if err != nil {
		panic(err)
	}
	return n
}

func println(a ...interface{}) {
	fmt.Fprintln(writer, a...)
}

package main

import (
	"bufio"
	"bytes"
	"errors"
	"io"
	"math/rand"
	"os"
	"strconv"
	"time"
	"unicode/utf8"
)

// ******************************** CODE STARTS ********************************

const ()

var ()

func solve() {
	n := readInt()
	firstName := make([]string, n)
	lastName := make([]string, n)
	for i := 0; i < n; i++ {
		firstName[i] = readString()
		lastName[i] = readString()
	}
	p := make([]int, n)
	for i := 0; i < n; i++ {
		p[i] = readInt() - 1
	}
	var last string
	for i := 0; i < n; i++ {
		if last > firstName[p[i]] && last > lastName[p[i]] {
			printString("NO\n")
			return
		}
		if firstName[p[i]] < lastName[p[i]] {
			if last < firstName[p[i]] {
				last = firstName[p[i]]
			} else {
				last = lastName[p[i]]
			}
		} else {
			if last < lastName[p[i]] {
				last = lastName[p[i]]
			} else {
				last = firstName[p[i]]
			}
		}
	}
	printString("YES\n")
}

// ********************************* CODE ENDS *********************************

// IO.

var (
	scanner *Scanner
	writer  *bufio.Writer
)

func main() {
	input := os.Stdin
	output := os.Stdout
	//	input, _ := os.Open("")
	//	output, _ := os.Create("")

	defer input.Close()
	defer output.Close()

	scanner = NewScanner(input)
	scanner.Split(bufio.ScanWords)

	writer = bufio.NewWriter(output)
	defer writer.Flush()

	rand.Seed(int64(time.Now().Nanosecond()))
	solve()
}

// Read.

func readString() string {
	scanner.Scan()
	ans := scanner.Text()
	return ans
}

func readLine() string {
	scanner.Split(bufio.ScanLines)
	defer scanner.Split(bufio.ScanWords)
	return readString()
}

func readInt() int {
	ans, _ := strconv.ParseInt(readString(), 10, 0)
	return int(ans)
}

func readInt64() int64 {
	ans, _ := strconv.ParseInt(readString(), 10, 64)
	return ans
}

func readFloat64() float64 {
	ans, _ := strconv.ParseFloat(readString(), 64)
	return ans
}

// Write.

func printString(value string) {
	writer.WriteString(value)
}

func printLine() {
	printString("\n")
}

func printSpace() {
	printString(" ")
}

func printInt(value int) {
	printString(strconv.FormatInt(int64(value), 10))
}

func printInt64(value int64) {
	printString(strconv.FormatInt(value, 10))
}

func printFloat64(value float64) {
	printString(strconv.FormatFloat(value, 'f', 20, 64))
}

// Tuple

type Tuple struct {
	a, b int
}

func (p Tuple) Equals(key Key) bool {
	return p.a == key.(Tuple).a
}

func (p Tuple) Less(key Key) bool {
	return p.a < key.(Tuple).a
}

type TupleSlice []Tuple

func (p TupleSlice) Len() int {
	return len(p)
}

func (p TupleSlice) Less(j, i int) bool {
	return p[j].a < p[i].a
}

func (p TupleSlice) Swap(j, i int) {
	p[j], p[i] = p[i], p[j]
}

// Min, max, abs.

func maxInt(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

func absInt(a int) int {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

func maxInt64(a, b int64) int64 {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt64(a, b int64) int64 {
	if a < b {
		return a
	} else {
		return b
	}
}

func absInt64(a int64) int64 {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

func maxFloat64(a, b float64) float64 {
	if a > b {
		return a
	} else {
		return b
	}
}

func minFloat64(a, b float64) float64 {
	if a < b {
		return a
	} else {
		return b
	}
}

func absFloat64(a float64) float64 {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

// Set Key interface implementations.

type Int int

func (p Int) Equals(key Key) bool {
	return int(p) == int(key.(Int))
}

func (p Int) Less(key Key) bool {
	return int(p) < int(key.(Int))
}

// Set.

type Key interface {
	Equals(key Key) bool
	Less(key Key) bool
}

type node struct {
	key   Key
	left  *node
	right *node
}

func newNode(key Key) *node {
	return &node{key, nil, nil}
}

type SplayTree struct {
	root *node
	tmp  *node
	len  int
}

func NewSplayTree() *SplayTree {
	return &SplayTree{nil, newNode(nil), 0}
}

func rotateLeft(x, p *node) {
	p.right = x.left
	x.left = p
}

func rotateRight(x, p *node) {
	p.left = x.right
	x.right = p
}

func (p *SplayTree) splay(x *node, key Key) *node {
	if x == nil {
		return nil
	}

	left := p.tmp
	right := p.tmp

	for {
		if key.Less(x.key) {
			y := x.left
			if y == nil {
				break
			}
			if key.Less(y.key) { // zig-zig
				rotateRight(y, x)
				x = y
				if x.left == nil {
					break
				}
			}
			// link right
			right.left = x
			right = x
			// move left
			x = x.left
		} else if x.key.Less(key) {
			y := x.right
			if y == nil {
				break
			}
			if y.key.Less(key) { // zig-zig
				rotateLeft(y, x)
				x = y
				if x.right == nil {
					break
				}
			}
			// link left
			left.right = x
			left = x
			// move right
			x = x.right
		} else {
			break
		}
	}

	left.right = x.left
	right.left = x.right
	x.left = p.tmp.right
	x.right = p.tmp.left

	return x
}

// left <= key < right
func (p *SplayTree) split(key Key) (left, right *node) {
	p.root = p.splay(p.root, key)
	if p.root.key.Equals(key) || p.root.key.Less(key) {
		right := p.root.right
		p.root.right = nil
		return p.root, right
	} else {
		left := p.root.left
		p.root.left = nil
		return left, p.root
	}
}

// keys from left tree must be less then keys from right tree
func (p *SplayTree) join(left, right *node) *node {
	if left == nil {
		return right
	} else if right == nil {
		return left
	}
	left = p.splay(left, right.key)
	left.right = right
	return left
}

type Set interface {
	Len() int
	Insert(key Key) error
	Find(key Key) bool
	Remove(key Key) error
}

func NewSet() Set {
	return Set(NewSplayTree())
}

func (p *SplayTree) Len() int {
	return p.len
}

func (p *SplayTree) Insert(key Key) error {
	if p.root == nil {
		p.root = newNode(key)
		p.len++
	} else {
		p.root = p.splay(p.root, key)
		if p.root.key.Equals(key) {
			return errors.New("Such key already exists")
		} else {
			left, right := p.split(key)
			p.root = newNode(key)
			p.root.left = left
			p.root.right = right
			p.len++
		}
	}
	return nil
}

func (p *SplayTree) Find(key Key) bool {
	if p.root == nil {
		return false
	}
	p.root = p.splay(p.root, key)
	return p.root.key.Equals(key)
}

func (p *SplayTree) Remove(key Key) error {
	p.root = p.splay(p.root, key)
	if p.root == nil || !p.root.key.Equals(key) {
		return errors.New("Such key doesn't exist")
	}
	p.root = p.join(p.split(key))
	return nil
}

// Copied scan.go
// Scanner provides a convenient interface for reading data such as
// a file of newline-delimited lines of text. Successive calls to
// the Scan method will step through the 'tokens' of a file, skipping
// the bytes between the tokens. The specification of a token is
// defined by a split function of type SplitFunc; the default split
// function breaks the input into lines with line termination stripped. Split
// functions are defined in this package for scanning a file into
// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
// client may instead provide a custom split function.
//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the buffer. When a scan stops, the reader may have
// advanced arbitrarily far past the last token. Programs that need more
// control over error handling or large tokens, or must run sequential scans
// on a reader, should use bufio.Reader instead.
//
type Scanner struct {
	r            io.Reader // The reader provided by the client.
	split        SplitFunc // The function to split the tokens.
	maxTokenSize int       // Maximum size of a token; modified by tests.
	token        []byte    // Last token returned by split.
	buf          []byte    // Buffer used as argument to split.
	start        int       // First non-processed byte in buf.
	end          int       // End of data in buf.
	err          error     // Sticky error.
}

// SplitFunc is the signature of the split function used to tokenize the
// input. The arguments are an initial substring of the remaining unprocessed
// data and a flag, atEOF, that reports whether the Reader has no more data
// to give. The return values are the number of bytes to advance the input
// and the next token to return to the user, plus an error, if any. If the
// data does not yet hold a complete token, for instance if it has no newline
// while scanning lines, SplitFunc can return (0, nil, nil) to signal the
// Scanner to read more data into the slice and try again with a longer slice
// starting at the same point in the input.
//
// If the returned error is non-nil, scanning stops and the error
// is returned to the client.
//
// The function is never called with an empty data slice unless atEOF
// is true. If atEOF is true, however, data may be non-empty and,
// as always, holds unprocessed text.
type SplitFunc func(data []byte, atEOF bool) (advance int, token []byte, err error)

// Errors returned by Scanner.
var (
	ErrTooLong         = errors.New("bufio.Scanner: token too long")
	ErrNegativeAdvance = errors.New("bufio.Scanner: SplitFunc returns negative advance count")
	ErrAdvanceTooFar   = errors.New("bufio.Scanner: SplitFunc returns advance count beyond input")
)

const (
	// Maximum size used to buffer a token. The actual maximum token size
	// may be smaller as the buffer may need to include, for instance, a newline.
	MaxScanTokenSize = 1 << 20
)

// NewScanner returns a new Scanner to read from r.
// The split function defaults to ScanLines.
func NewScanner(r io.Reader) *Scanner {
	return &Scanner{
		r:            r,
		split:        ScanLines,
		maxTokenSize: MaxScanTokenSize,
		buf:          make([]byte, 4096), // Plausible starting size; needn't be large.
	}
}

// Err returns the first non-EOF error that was encountered by the Scanner.
func (s *Scanner) Err() error {
	if s.err == io.EOF {
		return nil
	}
	return s.err
}

// Bytes returns the most recent token generated by a call to Scan.
// The underlying array may point to data that will be overwritten
// by a subsequent call to Scan. It does no allocation.
func (s *Scanner) Bytes() []byte {
	return s.token
}

// Text returns the most recent token generated by a call to Scan
// as a newly allocated string holding its bytes.
func (s *Scanner) Text() string {
	return string(s.token)
}

// Scan advances the Scanner to the next token, which will then be
// available through the Bytes or Text method. It returns false when the
// scan stops, either by reaching the end of the input or an error.
// After Scan returns false, the Err method will return any error that
// occurred during scanning, except that if it was io.EOF, Err
// will return nil.
func (s *Scanner) Scan() bool {
	// Loop until we have a token.
	for {
		// See if we can get a token with what we already have.
		if s.end > s.start {
			advance, token, err := s.split(s.buf[s.start:s.end], s.err != nil)
			if err != nil {
				s.setErr(err)
				return false
			}
			if !s.advance(advance) {
				return false
			}
			s.token = token
			if token != nil {
				return true
			}
		}
		// We cannot generate a token with what we are holding.
		// If we've already hit EOF or an I/O error, we are done.
		if s.err != nil {
			// Shut it down.
			s.start = 0
			s.end = 0
			return false
		}
		// Must read more data.
		// First, shift data to beginning of buffer if there's lots of empty space
		// or space is neded.
		if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
			copy(s.buf, s.buf[s.start:s.end])
			s.end -= s.start
			s.start = 0
		}
		// Is the buffer full? If so, resize.
		if s.end == len(s.buf) {
			if len(s.buf) >= s.maxTokenSize {
				s.setErr(ErrTooLong)
				return false
			}
			newSize := len(s.buf) * 2
			if newSize > s.maxTokenSize {
				newSize = s.maxTokenSize
			}
			newBuf := make([]byte, newSize)
			copy(newBuf, s.buf[s.start:s.end])
			s.buf = newBuf
			s.end -= s.start
			s.start = 0
			continue
		}
		// Finally we can read some input. Make sure we don't get stuck with
		// a misbehaving Reader. Officially we don't need to do this, but let's
		// be extra careful: Scanner is for safe, simple jobs.
		for loop := 0; ; {
			n, err := s.r.Read(s.buf[s.end:len(s.buf)])
			s.end += n
			if err != nil {
				s.setErr(err)
				break
			}
			if n > 0 {
				break
			}
			loop++
			if loop > 100 {
				s.setErr(io.ErrNoProgress)
				break
			}
		}
	}
}

// advance consumes n bytes of the buffer. It reports whether the advance was legal.
func (s *Scanner) advance(n int) bool {
	if n < 0 {
		s.setErr(ErrNegativeAdvance)
		return false
	}
	if n > s.end-s.start {
		s.setErr(ErrAdvanceTooFar)
		return false
	}
	s.start += n
	return true
}

// setErr records the first error encountered.
func (s *Scanner) setErr(err error) {
	if s.err == nil || s.err == io.EOF {
		s.err = err
	}
}

// Split sets the split function for the Scanner. If called, it must be
// called before Scan. The default split function is ScanLines.
func (s *Scanner) Split(split SplitFunc) {
	s.split = split
}

// Split functions

// ScanBytes is a split function for a Scanner that returns each byte as a token.
func ScanBytes(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	return 1, data[0:1], nil
}

var errorRune = []byte(string(utf8.RuneError))

// ScanRunes is a split function for a Scanner that returns each
// UTF-8-encoded rune as a token. The sequence of runes returned is
// equivalent to that from a range loop over the input as a string, which
// means that erroneous UTF-8 encodings translate to U+FFFD = "\xef\xbf\xbd".
// Because of the Scan interface, this makes it impossible for the client to
// distinguish correctly encoded replacement runes from encoding errors.
func ScanRunes(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}

	// Fast path 1: ASCII.
	if data[0] < utf8.RuneSelf {
		return 1, data[0:1], nil
	}

	// Fast path 2: Correct UTF-8 decode without error.
	_, width := utf8.DecodeRune(data)
	if width > 1 {
		// It's a valid encoding. Width cannot be one for a correctly encoded
		// non-ASCII rune.
		return width, data[0:width], nil
	}

	// We know it's an error: we have width==1 and implicitly r==utf8.RuneError.
	// Is the error because there wasn't a full rune to be decoded?
	// FullRune distinguishes correctly between erroneous and incomplete encodings.
	if !atEOF && !utf8.FullRune(data) {
		// Incomplete; get more bytes.
		return 0, nil, nil
	}

	// We have a real UTF-8 encoding error. Return a properly encoded error rune
	// but advance only one byte. This matches the behavior of a range loop over
	// an incorrectly encoded string.
	return 1, errorRune, nil
}

// dropCR drops a terminal \r from the data.
func dropCR(data []byte) []byte {
	if len(data) > 0 && data[len(data)-1] == '\r' {
		return data[0 : len(data)-1]
	}
	return data
}

// ScanLines is a split function for a Scanner that returns each line of
// text, stripped of any trailing end-of-line marker. The returned line may
// be empty. The end-of-line marker is one optional carriage return followed
// by one mandatory newline. In regular expression notation, it is `\r?\n`.
// The last non-empty line of input will be returned even if it has no
// newline.
func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	if i := bytes.IndexByte(data, '\n'); i >= 0 {
		// We have a full newline-terminated line.
		return i + 1, dropCR(data[0:i]), nil
	}
	// If we're at EOF, we have a final, non-terminated line. Return it.
	if atEOF {
		return len(data), dropCR(data), nil
	}
	// Request more data.
	return 0, nil, nil
}

// isSpace reports whether the character is a Unicode white space character.
// We avoid dependency on the unicode package, but check validity of the implementation
// in the tests.
func isSpace(r rune) bool {
	if r <= '\u00FF' {
		// Obvious ASCII ones: \t through \r plus space. Plus two Latin-1 oddballs.
		switch r {
		case ' ', '\t', '\n', '\v', '\f', '\r':
			return true
		case '\u0085', '\u00A0':
			return true
		}
		return false
	}
	// High-valued ones.
	if '\u2000' <= r && r <= '\u200a' {
		return true
	}
	switch r {
	case '\u1680', '\u180e', '\u2028', '\u2029', '\u202f', '\u205f', '\u3000':
		return true
	}
	return false
}

// ScanWords is a split function for a Scanner that returns each
// space-separated word of text, with surrounding spaces deleted. It will
// never return an empty string. The definition of space is set by
// unicode.IsSpace.
func ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error) {
	// Skip leading spaces.
	start := 0
	for width := 0; start < len(data); start += width {
		var r rune
		r, width = utf8.DecodeRune(data[start:])
		if !isSpace(r) {
			break
		}
	}
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	// Scan until space, marking end of word.
	for width, i := 0, start; i < len(data); i += width {
		var r rune
		r, width = utf8.DecodeRune(data[i:])
		if isSpace(r) {
			return i + width, data[start:i], nil
		}
	}
	// If we're at EOF, we have a final, non-empty, non-terminated word. Return it.
	if atEOF && len(data) > start {
		return len(data), data[start:], nil
	}
	// Request more data.
	return 0, nil, nil
}

package main

import (
	"bufio"
	"bytes"
	"errors"
	"io"
	"math/rand"
	"os"
	"strconv"
	"time"
	"unicode/utf8"
)

// ******************************** CODE STARTS ********************************

const ()

var (
)

func solve() {
	n := readInt()
	firstName := make([]string, n)
	lastName := make([]string, n)
	for i := 0; i < n; i++ {
		firstName[i] = readString()
		lastName[i] = readString()
	}
	p := make([]int, n)
	for i := 0; i < n; i++ {
		p[i] = readInt() - 1
	}
	var last string
	for i := 0; i < n; i++ {
		if last > firstName[p[i]] && last > lastName[p[i]] {
			printString("NO\n")
			return
		}
		if firstName[p[i]] < lastName[p[i]] {
			if last < firstName[p[i]] {
				last = firstName[p[i]]
			} else {
				last = lastName[p[i]]
			}
		} else {
			if last < lastName[p[i]] {
				last = lastName[p[i]]
			} else {
				last = firstName[p[i]]
			}
		}
	}
	printString("YES\n")
}

// ********************************* CODE ENDS *********************************

// IO.

var (
	scanner *Scanner
	writer  *bufio.Writer
)

func main() {
	input := os.Stdin
	output := os.Stdout
	//	input, _ := os.Open("")
	//	output, _ := os.Create("")

	defer input.Close()
	defer output.Close()

	scanner = NewScanner(input)
	scanner.Split(bufio.ScanWords)

	writer = bufio.NewWriter(output)
	defer writer.Flush()

	rand.Seed(int64(time.Now().Nanosecond()))
	solve()
}

// Read.

func readString() string {
	scanner.Scan()
	ans := scanner.Text()
	return ans
}

func readLine() string {
	scanner.Split(bufio.ScanLines)
	defer scanner.Split(bufio.ScanWords)
	return readString()
}

func readInt() int {
	ans, _ := strconv.ParseInt(readString(), 10, 0)
	return int(ans)
}

func readInt64() int64 {
	ans, _ := strconv.ParseInt(readString(), 10, 64)
	return ans
}

func readFloat64() float64 {
	ans, _ := strconv.ParseFloat(readString(), 64)
	return ans
}

// Write.

func printString(value string) {
	writer.WriteString(value)
}

func printLine() {
	printString("\n")
}

func printSpace() {
	printString(" ")
}

func printInt(value int) {
	printString(strconv.FormatInt(int64(value), 10))
}

func printInt64(value int64) {
	printString(strconv.FormatInt(value, 10))
}

func printFloat64(value float64) {
	printString(strconv.FormatFloat(value, 'f', 20, 64))
}

// Tuple

type Tuple struct {
	a, b int
}

func (p Tuple) Equals(key Key) bool {
	return p.a == key.(Tuple).a
}

func (p Tuple) Less(key Key) bool {
	return p.a < key.(Tuple).a
}

type TupleSlice []Tuple

func (p TupleSlice) Len() int {
	return len(p)
}

func (p TupleSlice) Less(j, i int) bool {
	return p[j].a < p[i].a
}

func (p TupleSlice) Swap(j, i int) {
	p[j], p[i] = p[i], p[j]
}

// Min, max, abs.

func maxInt(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

func absInt(a int) int {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

func maxInt64(a, b int64) int64 {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt64(a, b int64) int64 {
	if a < b {
		return a
	} else {
		return b
	}
}

func absInt64(a int64) int64 {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

func maxFloat64(a, b float64) float64 {
	if a > b {
		return a
	} else {
		return b
	}
}

func minFloat64(a, b float64) float64 {
	if a < b {
		return a
	} else {
		return b
	}
}

func absFloat64(a float64) float64 {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

// Set Key interface implementations.

type Int int

func (p Int) Equals(key Key) bool {
	return int(p) == int(key.(Int))
}

func (p Int) Less(key Key) bool {
	return int(p) < int(key.(Int))
}

// Set.

type Key interface {
	Equals(key Key) bool
	Less(key Key) bool
}

type node struct {
	key   Key
	left  *node
	right *node
}

func newNode(key Key) *node {
	return &node{key, nil, nil}
}

type SplayTree struct {
	root *node
	tmp  *node
	len  int
}

func NewSplayTree() *SplayTree {
	return &SplayTree{nil, newNode(nil), 0}
}

func rotateLeft(x, p *node) {
	p.right = x.left
	x.left = p
}

func rotateRight(x, p *node) {
	p.left = x.right
	x.right = p
}

func (p *SplayTree) splay(x *node, key Key) *node {
	if x == nil {
		return nil
	}

	left := p.tmp
	right := p.tmp

	for {
		if key.Less(x.key) {
			y := x.left
			if y == nil {
				break
			}
			if key.Less(y.key) { // zig-zig
				rotateRight(y, x)
				x = y
				if x.left == nil {
					break
				}
			}
			// link right
			right.left = x
			right = x
			// move left
			x = x.left
		} else if x.key.Less(key) {
			y := x.right
			if y == nil {
				break
			}
			if y.key.Less(key) { // zig-zig
				rotateLeft(y, x)
				x = y
				if x.right == nil {
					break
				}
			}
			// link left
			left.right = x
			left = x
			// move right
			x = x.right
		} else {
			break
		}
	}

	left.right = x.left
	right.left = x.right
	x.left = p.tmp.right
	x.right = p.tmp.left

	return x
}

// left <= key < right
func (p *SplayTree) split(key Key) (left, right *node) {
	p.root = p.splay(p.root, key)
	if p.root.key.Equals(key) || p.root.key.Less(key) {
		right := p.root.right
		p.root.right = nil
		return p.root, right
	} else {
		left := p.root.left
		p.root.left = nil
		return left, p.root
	}
}

// keys from left tree must be less then keys from right tree
func (p *SplayTree) join(left, right *node) *node {
	if left == nil {
		return right
	} else if right == nil {
		return left
	}
	left = p.splay(left, right.key)
	left.right = right
	return left
}

type Set interface {
	Len() int
	Insert(key Key) error
	Find(key Key) bool
	Remove(key Key) error
}

func NewSet() Set {
	return Set(NewSplayTree())
}

func (p *SplayTree) Len() int {
	return p.len
}

func (p *SplayTree) Insert(key Key) error {
	if p.root == nil {
		p.root = newNode(key)
		p.len++
	} else {
		p.root = p.splay(p.root, key)
		if p.root.key.Equals(key) {
			return errors.New("Such key already exists")
		} else {
			left, right := p.split(key)
			p.root = newNode(key)
			p.root.left = left
			p.root.right = right
			p.len++
		}
	}
	return nil
}

func (p *SplayTree) Find(key Key) bool {
	if p.root == nil {
		return false
	}
	p.root = p.splay(p.root, key)
	return p.root.key.Equals(key)
}

func (p *SplayTree) Remove(key Key) error {
	p.root = p.splay(p.root, key)
	if p.root == nil || !p.root.key.Equals(key) {
		return errors.New("Such key doesn't exist")
	}
	p.root = p.join(p.split(key))
	return nil
}

// Copied scan.go
// Scanner provides a convenient interface for reading data such as
// a file of newline-delimited lines of text. Successive calls to
// the Scan method will step through the 'tokens' of a file, skipping
// the bytes between the tokens. The specification of a token is
// defined by a split function of type SplitFunc; the default split
// function breaks the input into lines with line termination stripped. Split
// functions are defined in this package for scanning a file into
// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
// client may instead provide a custom split function.
//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the buffer. When a scan stops, the reader may have
// advanced arbitrarily far past the last token. Programs that need more
// control over error handling or large tokens, or must run sequential scans
// on a reader, should use bufio.Reader instead.
//
type Scanner struct {
	r            io.Reader // The reader provided by the client.
	split        SplitFunc // The function to split the tokens.
	maxTokenSize int       // Maximum size of a token; modified by tests.
	token        []byte    // Last token returned by split.
	buf          []byte    // Buffer used as argument to split.
	start        int       // First non-processed byte in buf.
	end          int       // End of data in buf.
	err          error     // Sticky error.
}

// SplitFunc is the signature of the split function used to tokenize the
// input. The arguments are an initial substring of the remaining unprocessed
// data and a flag, atEOF, that reports whether the Reader has no more data
// to give. The return values are the number of bytes to advance the input
// and the next token to return to the user, plus an error, if any. If the
// data does not yet hold a complete token, for instance if it has no newline
// while scanning lines, SplitFunc can return (0, nil, nil) to signal the
// Scanner to read more data into the slice and try again with a longer slice
// starting at the same point in the input.
//
// If the returned error is non-nil, scanning stops and the error
// is returned to the client.
//
// The function is never called with an empty data slice unless atEOF
// is true. If atEOF is true, however, data may be non-empty and,
// as always, holds unprocessed text.
type SplitFunc func(data []byte, atEOF bool) (advance int, token []byte, err error)

// Errors returned by Scanner.
var (
	ErrTooLong         = errors.New("bufio.Scanner: token too long")
	ErrNegativeAdvance = errors.New("bufio.Scanner: SplitFunc returns negative advance count")
	ErrAdvanceTooFar   = errors.New("bufio.Scanner: SplitFunc returns advance count beyond input")
)

const (
	// Maximum size used to buffer a token. The actual maximum token size
	// may be smaller as the buffer may need to include, for instance, a newline.
	MaxScanTokenSize = 1 << 20
)

// NewScanner returns a new Scanner to read from r.
// The split function defaults to ScanLines.
func NewScanner(r io.Reader) *Scanner {
	return &Scanner{
		r:            r,
		split:        ScanLines,
		maxTokenSize: MaxScanTokenSize,
		buf:          make([]byte, 4096), // Plausible starting size; needn't be large.
	}
}

// Err returns the first non-EOF error that was encountered by the Scanner.
func (s *Scanner) Err() error {
	if s.err == io.EOF {
		return nil
	}
	return s.err
}

// Bytes returns the most recent token generated by a call to Scan.
// The underlying array may point to data that will be overwritten
// by a subsequent call to Scan. It does no allocation.
func (s *Scanner) Bytes() []byte {
	return s.token
}

// Text returns the most recent token generated by a call to Scan
// as a newly allocated string holding its bytes.
func (s *Scanner) Text() string {
	return string(s.token)
}

// Scan advances the Scanner to the next token, which will then be
// available through the Bytes or Text method. It returns false when the
// scan stops, either by reaching the end of the input or an error.
// After Scan returns false, the Err method will return any error that
// occurred during scanning, except that if it was io.EOF, Err
// will return nil.
func (s *Scanner) Scan() bool {
	// Loop until we have a token.
	for {
		// See if we can get a token with what we already have.
		if s.end > s.start {
			advance, token, err := s.split(s.buf[s.start:s.end], s.err != nil)
			if err != nil {
				s.setErr(err)
				return false
			}
			if !s.advance(advance) {
				return false
			}
			s.token = token
			if token != nil {
				return true
			}
		}
		// We cannot generate a token with what we are holding.
		// If we've already hit EOF or an I/O error, we are done.
		if s.err != nil {
			// Shut it down.
			s.start = 0
			s.end = 0
			return false
		}
		// Must read more data.
		// First, shift data to beginning of buffer if there's lots of empty space
		// or space is neded.
		if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
			copy(s.buf, s.buf[s.start:s.end])
			s.end -= s.start
			s.start = 0
		}
		// Is the buffer full? If so, resize.
		if s.end == len(s.buf) {
			if len(s.buf) >= s.maxTokenSize {
				s.setErr(ErrTooLong)
				return false
			}
			newSize := len(s.buf) * 2
			if newSize > s.maxTokenSize {
				newSize = s.maxTokenSize
			}
			newBuf := make([]byte, newSize)
			copy(newBuf, s.buf[s.start:s.end])
			s.buf = newBuf
			s.end -= s.start
			s.start = 0
			continue
		}
		// Finally we can read some input. Make sure we don't get stuck with
		// a misbehaving Reader. Officially we don't need to do this, but let's
		// be extra careful: Scanner is for safe, simple jobs.
		for loop := 0; ; {
			n, err := s.r.Read(s.buf[s.end:len(s.buf)])
			s.end += n
			if err != nil {
				s.setErr(err)
				break
			}
			if n > 0 {
				break
			}
			loop++
			if loop > 100 {
				s.setErr(io.ErrNoProgress)
				break
			}
		}
	}
}

// advance consumes n bytes of the buffer. It reports whether the advance was legal.
func (s *Scanner) advance(n int) bool {
	if n < 0 {
		s.setErr(ErrNegativeAdvance)
		return false
	}
	if n > s.end-s.start {
		s.setErr(ErrAdvanceTooFar)
		return false
	}
	s.start += n
	return true
}

// setErr records the first error encountered.
func (s *Scanner) setErr(err error) {
	if s.err == nil || s.err == io.EOF {
		s.err = err
	}
}

// Split sets the split function for the Scanner. If called, it must be
// called before Scan. The default split function is ScanLines.
func (s *Scanner) Split(split SplitFunc) {
	s.split = split
}

// Split functions

// ScanBytes is a split function for a Scanner that returns each byte as a token.
func ScanBytes(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	return 1, data[0:1], nil
}

var errorRune = []byte(string(utf8.RuneError))

// ScanRunes is a split function for a Scanner that returns each
// UTF-8-encoded rune as a token. The sequence of runes returned is
// equivalent to that from a range loop over the input as a string, which
// means that erroneous UTF-8 encodings translate to U+FFFD = "\xef\xbf\xbd".
// Because of the Scan interface, this makes it impossible for the client to
// distinguish correctly encoded replacement runes from encoding errors.
func ScanRunes(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}

	// Fast path 1: ASCII.
	if data[0] < utf8.RuneSelf {
		return 1, data[0:1], nil
	}

	// Fast path 2: Correct UTF-8 decode without error.
	_, width := utf8.DecodeRune(data)
	if width > 1 {
		// It's a valid encoding. Width cannot be one for a correctly encoded
		// non-ASCII rune.
		return width, data[0:width], nil
	}

	// We know it's an error: we have width==1 and implicitly r==utf8.RuneError.
	// Is the error because there wasn't a full rune to be decoded?
	// FullRune distinguishes correctly between erroneous and incomplete encodings.
	if !atEOF && !utf8.FullRune(data) {
		// Incomplete; get more bytes.
		return 0, nil, nil
	}

	// We have a real UTF-8 encoding error. Return a properly encoded error rune
	// but advance only one byte. This matches the behavior of a range loop over
	// an incorrectly encoded string.
	return 1, errorRune, nil
}

// dropCR drops a terminal \r from the data.
func dropCR(data []byte) []byte {
	if len(data) > 0 && data[len(data)-1] == '\r' {
		return data[0 : len(data)-1]
	}
	return data
}

// ScanLines is a split function for a Scanner that returns each line of
// text, stripped of any trailing end-of-line marker. The returned line may
// be empty. The end-of-line marker is one optional carriage return followed
// by one mandatory newline. In regular expression notation, it is `\r?\n`.
// The last non-empty line of input will be returned even if it has no
// newline.
func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	if i := bytes.IndexByte(data, '\n'); i >= 0 {
		// We have a full newline-terminated line.
		return i + 1, dropCR(data[0:i]), nil
	}
	// If we're at EOF, we have a final, non-terminated line. Return it.
	if atEOF {
		return len(data), dropCR(data), nil
	}
	// Request more data.
	return 0, nil, nil
}

// isSpace reports whether the character is a Unicode white space character.
// We avoid dependency on the unicode package, but check validity of the implementation
// in the tests.
func isSpace(r rune) bool {
	if r <= '\u00FF' {
		// Obvious ASCII ones: \t through \r plus space. Plus two Latin-1 oddballs.
		switch r {
		case ' ', '\t', '\n', '\v', '\f', '\r':
			return true
		case '\u0085', '\u00A0':
			return true
		}
		return false
	}
	// High-valued ones.
	if '\u2000' <= r && r <= '\u200a' {
		return true
	}
	switch r {
	case '\u1680', '\u180e', '\u2028', '\u2029', '\u202f', '\u205f', '\u3000':
		return true
	}
	return false
}

// ScanWords is a split function for a Scanner that returns each
// space-separated word of text, with surrounding spaces deleted. It will
// never return an empty string. The definition of space is set by
// unicode.IsSpace.
func ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error) {
	// Skip leading spaces.
	start := 0
	for width := 0; start < len(data); start += width {
		var r rune
		r, width = utf8.DecodeRune(data[start:])
		if !isSpace(r) {
			break
		}
	}
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	// Scan until space, marking end of word.
	for width, i := 0, start; i < len(data); i += width {
		var r rune
		r, width = utf8.DecodeRune(data[i:])
		if isSpace(r) {
			return i + width, data[start:i], nil
		}
	}
	// If we're at EOF, we have a final, non-empty, non-terminated word. Return it.
	if atEOF && len(data) > start {
		return len(data), data[start:], nil
	}
	// Request more data.
	return 0, nil, nil
}

package main

import (
    "bufio"
    _ "fmt"
    "os"
    _ "sort"
    "strconv"
)

type member struct {
    name    string
    surname string
}

type Members []member

func (m Members) Len() int           { return len(m) }
func (m Members) Swap(i, j int)      { m[i], m[j] = m[j], m[i] }
func (m Members) Less(i, j int) bool { return m[i].name < m[j].name }

var scanner *bufio.Scanner = bufio.NewScanner(os.Stdin)
var writer *bufio.Writer = bufio.NewWriter(os.Stdout)
var members []member
var members2 []member

func ReadInt32() int {
    scanner.Scan()
    ans, _ := strconv.Atoi(scanner.Text())
    return ans
}

func ReadString() string {
    scanner.Scan()
    return scanner.Text()
}

func main() {
    var pos int
    var s, mmin, mmax string
    defer writer.Flush()
    scanner.Split(bufio.ScanWords)

    n := ReadInt32()
    members = make([]member, n)
    members2 = make([]member, n)
    for i := 0; i < n; i++ {
        members[i].name = ReadString()
        members[i].surname = ReadString()
    }

    for i := 0; i < n; i++ {
        pos = ReadInt32() - 1
        members2[i] = members[pos]
    }

    f := true
    if members2[0].name < members2[0].surname {
        s = members2[0].name
    } else {
        s = members2[0].surname
    }

    for i := 1; (i < n) && f; i++ {
        if members2[i].name < members2[i].surname {
            mmin = members2[i].name
            mmax = members2[i].surname
        } else {
            mmin = members2[i].surname
            mmax = members2[i].name
        }

        if mmin > s {
            s = mmin
        } else if mmax > s {
            s = mmax
        } else {
            f = false
        }
    }

    if f {
        writer.WriteString("YES\n")
    } else {
        writer.WriteString("NO\n")
    }
}

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

type name struct {
	first string
	last  string
}

func min(a, b string) string {
	if a < b {
		return a
	}
	return b
}

func main() {
	var n int
	fmt.Scan(&n)

	names := make([]name, n, n)
	bs := bufio.NewScanner(os.Stdin)
	bs.Split(bufio.ScanWords)
	for i := 0; i < n; i++ {
		bs.Scan()
		names[i].first = bs.Text()
		bs.Scan()
		names[i].last = bs.Text()
	}

	pn := make([]int, n, n)
	for i := 0; i < n; i++ {
		bs.Scan()
		pn[i], _ = strconv.Atoi(bs.Text())
	}

	ans := true
	handle := ""
	for i := 0; i < n; i++ {
		index := pn[i] - 1
		if i == 0 {
			handle = min(names[index].first, names[index].last)
		} else {
			if handle < names[index].first && handle < names[index].last {
				handle = min(names[index].first, names[index].last)
			} else if handle < names[index].first {
				handle = names[index].first
			} else if handle < names[index].last {
				handle = names[index].last
			} else {
				ans = false
				break
			}
		}
	}

	if ans {
		fmt.Println("YES")
	} else {
		fmt.Println("NO")
	}
}

package main

import (
	"bufio"
	"bytes"
	"errors"
	"io"
	"math/rand"
	"os"
	"strconv"
	"time"
	"unicode/utf8"
)

// ******************************** CODE STARTS ********************************

const ()

var (
)

func solve() {
	n := readInt()
	firstName := make([]string, n)
	lastName := make([]string, n)
	for i := 0; i < n; i++ {
		firstName[i] = readString()
		lastName[i] = readString()
	}
	p := make([]int, n)
	for i := 0; i < n; i++ {
		p[i] = readInt() - 1
	}
	var last string
	for i := 0; i < n; i++ {
		if last > firstName[p[i]] && last > lastName[p[i]] {
			printString("NO\n")
			return
		}
		if firstName[p[i]] < lastName[p[i]] {
			last = firstName[p[i]]
		} else {
			last = lastName[p[i]]
		}
	}
	printString("YES\n")
}

// ********************************* CODE ENDS *********************************

// IO.

var (
	scanner *Scanner
	writer  *bufio.Writer
)

func main() {
	input := os.Stdin
	output := os.Stdout
	//	input, _ := os.Open("")
	//	output, _ := os.Create("")

	defer input.Close()
	defer output.Close()

	scanner = NewScanner(input)
	scanner.Split(bufio.ScanWords)

	writer = bufio.NewWriter(output)
	defer writer.Flush()

	rand.Seed(int64(time.Now().Nanosecond()))
	solve()
}

// Read.

func readString() string {
	scanner.Scan()
	ans := scanner.Text()
	return ans
}

func readLine() string {
	scanner.Split(bufio.ScanLines)
	defer scanner.Split(bufio.ScanWords)
	return readString()
}

func readInt() int {
	ans, _ := strconv.ParseInt(readString(), 10, 0)
	return int(ans)
}

func readInt64() int64 {
	ans, _ := strconv.ParseInt(readString(), 10, 64)
	return ans
}

func readFloat64() float64 {
	ans, _ := strconv.ParseFloat(readString(), 64)
	return ans
}

// Write.

func printString(value string) {
	writer.WriteString(value)
}

func printLine() {
	printString("\n")
}

func printSpace() {
	printString(" ")
}

func printInt(value int) {
	printString(strconv.FormatInt(int64(value), 10))
}

func printInt64(value int64) {
	printString(strconv.FormatInt(value, 10))
}

func printFloat64(value float64) {
	printString(strconv.FormatFloat(value, 'f', 20, 64))
}

// Tuple

type Tuple struct {
	a, b int
}

func (p Tuple) Equals(key Key) bool {
	return p.a == key.(Tuple).a
}

func (p Tuple) Less(key Key) bool {
	return p.a < key.(Tuple).a
}

type TupleSlice []Tuple

func (p TupleSlice) Len() int {
	return len(p)
}

func (p TupleSlice) Less(j, i int) bool {
	return p[j].a < p[i].a
}

func (p TupleSlice) Swap(j, i int) {
	p[j], p[i] = p[i], p[j]
}

// Min, max, abs.

func maxInt(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

func absInt(a int) int {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

func maxInt64(a, b int64) int64 {
	if a > b {
		return a
	} else {
		return b
	}
}

func minInt64(a, b int64) int64 {
	if a < b {
		return a
	} else {
		return b
	}
}

func absInt64(a int64) int64 {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

func maxFloat64(a, b float64) float64 {
	if a > b {
		return a
	} else {
		return b
	}
}

func minFloat64(a, b float64) float64 {
	if a < b {
		return a
	} else {
		return b
	}
}

func absFloat64(a float64) float64 {
	if a > 0 {
		return a
	} else {
		return -a
	}
}

// Set Key interface implementations.

type Int int

func (p Int) Equals(key Key) bool {
	return int(p) == int(key.(Int))
}

func (p Int) Less(key Key) bool {
	return int(p) < int(key.(Int))
}

// Set.

type Key interface {
	Equals(key Key) bool
	Less(key Key) bool
}

type node struct {
	key   Key
	left  *node
	right *node
}

func newNode(key Key) *node {
	return &node{key, nil, nil}
}

type SplayTree struct {
	root *node
	tmp  *node
	len  int
}

func NewSplayTree() *SplayTree {
	return &SplayTree{nil, newNode(nil), 0}
}

func rotateLeft(x, p *node) {
	p.right = x.left
	x.left = p
}

func rotateRight(x, p *node) {
	p.left = x.right
	x.right = p
}

func (p *SplayTree) splay(x *node, key Key) *node {
	if x == nil {
		return nil
	}

	left := p.tmp
	right := p.tmp

	for {
		if key.Less(x.key) {
			y := x.left
			if y == nil {
				break
			}
			if key.Less(y.key) { // zig-zig
				rotateRight(y, x)
				x = y
				if x.left == nil {
					break
				}
			}
			// link right
			right.left = x
			right = x
			// move left
			x = x.left
		} else if x.key.Less(key) {
			y := x.right
			if y == nil {
				break
			}
			if y.key.Less(key) { // zig-zig
				rotateLeft(y, x)
				x = y
				if x.right == nil {
					break
				}
			}
			// link left
			left.right = x
			left = x
			// move right
			x = x.right
		} else {
			break
		}
	}

	left.right = x.left
	right.left = x.right
	x.left = p.tmp.right
	x.right = p.tmp.left

	return x
}

// left <= key < right
func (p *SplayTree) split(key Key) (left, right *node) {
	p.root = p.splay(p.root, key)
	if p.root.key.Equals(key) || p.root.key.Less(key) {
		right := p.root.right
		p.root.right = nil
		return p.root, right
	} else {
		left := p.root.left
		p.root.left = nil
		return left, p.root
	}
}

// keys from left tree must be less then keys from right tree
func (p *SplayTree) join(left, right *node) *node {
	if left == nil {
		return right
	} else if right == nil {
		return left
	}
	left = p.splay(left, right.key)
	left.right = right
	return left
}

type Set interface {
	Len() int
	Insert(key Key) error
	Find(key Key) bool
	Remove(key Key) error
}

func NewSet() Set {
	return Set(NewSplayTree())
}

func (p *SplayTree) Len() int {
	return p.len
}

func (p *SplayTree) Insert(key Key) error {
	if p.root == nil {
		p.root = newNode(key)
		p.len++
	} else {
		p.root = p.splay(p.root, key)
		if p.root.key.Equals(key) {
			return errors.New("Such key already exists")
		} else {
			left, right := p.split(key)
			p.root = newNode(key)
			p.root.left = left
			p.root.right = right
			p.len++
		}
	}
	return nil
}

func (p *SplayTree) Find(key Key) bool {
	if p.root == nil {
		return false
	}
	p.root = p.splay(p.root, key)
	return p.root.key.Equals(key)
}

func (p *SplayTree) Remove(key Key) error {
	p.root = p.splay(p.root, key)
	if p.root == nil || !p.root.key.Equals(key) {
		return errors.New("Such key doesn't exist")
	}
	p.root = p.join(p.split(key))
	return nil
}

// Copied scan.go
// Scanner provides a convenient interface for reading data such as
// a file of newline-delimited lines of text. Successive calls to
// the Scan method will step through the 'tokens' of a file, skipping
// the bytes between the tokens. The specification of a token is
// defined by a split function of type SplitFunc; the default split
// function breaks the input into lines with line termination stripped. Split
// functions are defined in this package for scanning a file into
// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
// client may instead provide a custom split function.
//
// Scanning stops unrecoverably at EOF, the first I/O error, or a token too
// large to fit in the buffer. When a scan stops, the reader may have
// advanced arbitrarily far past the last token. Programs that need more
// control over error handling or large tokens, or must run sequential scans
// on a reader, should use bufio.Reader instead.
//
type Scanner struct {
	r            io.Reader // The reader provided by the client.
	split        SplitFunc // The function to split the tokens.
	maxTokenSize int       // Maximum size of a token; modified by tests.
	token        []byte    // Last token returned by split.
	buf          []byte    // Buffer used as argument to split.
	start        int       // First non-processed byte in buf.
	end          int       // End of data in buf.
	err          error     // Sticky error.
}

// SplitFunc is the signature of the split function used to tokenize the
// input. The arguments are an initial substring of the remaining unprocessed
// data and a flag, atEOF, that reports whether the Reader has no more data
// to give. The return values are the number of bytes to advance the input
// and the next token to return to the user, plus an error, if any. If the
// data does not yet hold a complete token, for instance if it has no newline
// while scanning lines, SplitFunc can return (0, nil, nil) to signal the
// Scanner to read more data into the slice and try again with a longer slice
// starting at the same point in the input.
//
// If the returned error is non-nil, scanning stops and the error
// is returned to the client.
//
// The function is never called with an empty data slice unless atEOF
// is true. If atEOF is true, however, data may be non-empty and,
// as always, holds unprocessed text.
type SplitFunc func(data []byte, atEOF bool) (advance int, token []byte, err error)

// Errors returned by Scanner.
var (
	ErrTooLong         = errors.New("bufio.Scanner: token too long")
	ErrNegativeAdvance = errors.New("bufio.Scanner: SplitFunc returns negative advance count")
	ErrAdvanceTooFar   = errors.New("bufio.Scanner: SplitFunc returns advance count beyond input")
)

const (
	// Maximum size used to buffer a token. The actual maximum token size
	// may be smaller as the buffer may need to include, for instance, a newline.
	MaxScanTokenSize = 1 << 20
)

// NewScanner returns a new Scanner to read from r.
// The split function defaults to ScanLines.
func NewScanner(r io.Reader) *Scanner {
	return &Scanner{
		r:            r,
		split:        ScanLines,
		maxTokenSize: MaxScanTokenSize,
		buf:          make([]byte, 4096), // Plausible starting size; needn't be large.
	}
}

// Err returns the first non-EOF error that was encountered by the Scanner.
func (s *Scanner) Err() error {
	if s.err == io.EOF {
		return nil
	}
	return s.err
}

// Bytes returns the most recent token generated by a call to Scan.
// The underlying array may point to data that will be overwritten
// by a subsequent call to Scan. It does no allocation.
func (s *Scanner) Bytes() []byte {
	return s.token
}

// Text returns the most recent token generated by a call to Scan
// as a newly allocated string holding its bytes.
func (s *Scanner) Text() string {
	return string(s.token)
}

// Scan advances the Scanner to the next token, which will then be
// available through the Bytes or Text method. It returns false when the
// scan stops, either by reaching the end of the input or an error.
// After Scan returns false, the Err method will return any error that
// occurred during scanning, except that if it was io.EOF, Err
// will return nil.
func (s *Scanner) Scan() bool {
	// Loop until we have a token.
	for {
		// See if we can get a token with what we already have.
		if s.end > s.start {
			advance, token, err := s.split(s.buf[s.start:s.end], s.err != nil)
			if err != nil {
				s.setErr(err)
				return false
			}
			if !s.advance(advance) {
				return false
			}
			s.token = token
			if token != nil {
				return true
			}
		}
		// We cannot generate a token with what we are holding.
		// If we've already hit EOF or an I/O error, we are done.
		if s.err != nil {
			// Shut it down.
			s.start = 0
			s.end = 0
			return false
		}
		// Must read more data.
		// First, shift data to beginning of buffer if there's lots of empty space
		// or space is neded.
		if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
			copy(s.buf, s.buf[s.start:s.end])
			s.end -= s.start
			s.start = 0
		}
		// Is the buffer full? If so, resize.
		if s.end == len(s.buf) {
			if len(s.buf) >= s.maxTokenSize {
				s.setErr(ErrTooLong)
				return false
			}
			newSize := len(s.buf) * 2
			if newSize > s.maxTokenSize {
				newSize = s.maxTokenSize
			}
			newBuf := make([]byte, newSize)
			copy(newBuf, s.buf[s.start:s.end])
			s.buf = newBuf
			s.end -= s.start
			s.start = 0
			continue
		}
		// Finally we can read some input. Make sure we don't get stuck with
		// a misbehaving Reader. Officially we don't need to do this, but let's
		// be extra careful: Scanner is for safe, simple jobs.
		for loop := 0; ; {
			n, err := s.r.Read(s.buf[s.end:len(s.buf)])
			s.end += n
			if err != nil {
				s.setErr(err)
				break
			}
			if n > 0 {
				break
			}
			loop++
			if loop > 100 {
				s.setErr(io.ErrNoProgress)
				break
			}
		}
	}
}

// advance consumes n bytes of the buffer. It reports whether the advance was legal.
func (s *Scanner) advance(n int) bool {
	if n < 0 {
		s.setErr(ErrNegativeAdvance)
		return false
	}
	if n > s.end-s.start {
		s.setErr(ErrAdvanceTooFar)
		return false
	}
	s.start += n
	return true
}

// setErr records the first error encountered.
func (s *Scanner) setErr(err error) {
	if s.err == nil || s.err == io.EOF {
		s.err = err
	}
}

// Split sets the split function for the Scanner. If called, it must be
// called before Scan. The default split function is ScanLines.
func (s *Scanner) Split(split SplitFunc) {
	s.split = split
}

// Split functions

// ScanBytes is a split function for a Scanner that returns each byte as a token.
func ScanBytes(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	return 1, data[0:1], nil
}

var errorRune = []byte(string(utf8.RuneError))

// ScanRunes is a split function for a Scanner that returns each
// UTF-8-encoded rune as a token. The sequence of runes returned is
// equivalent to that from a range loop over the input as a string, which
// means that erroneous UTF-8 encodings translate to U+FFFD = "\xef\xbf\xbd".
// Because of the Scan interface, this makes it impossible for the client to
// distinguish correctly encoded replacement runes from encoding errors.
func ScanRunes(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}

	// Fast path 1: ASCII.
	if data[0] < utf8.RuneSelf {
		return 1, data[0:1], nil
	}

	// Fast path 2: Correct UTF-8 decode without error.
	_, width := utf8.DecodeRune(data)
	if width > 1 {
		// It's a valid encoding. Width cannot be one for a correctly encoded
		// non-ASCII rune.
		return width, data[0:width], nil
	}

	// We know it's an error: we have width==1 and implicitly r==utf8.RuneError.
	// Is the error because there wasn't a full rune to be decoded?
	// FullRune distinguishes correctly between erroneous and incomplete encodings.
	if !atEOF && !utf8.FullRune(data) {
		// Incomplete; get more bytes.
		return 0, nil, nil
	}

	// We have a real UTF-8 encoding error. Return a properly encoded error rune
	// but advance only one byte. This matches the behavior of a range loop over
	// an incorrectly encoded string.
	return 1, errorRune, nil
}

// dropCR drops a terminal \r from the data.
func dropCR(data []byte) []byte {
	if len(data) > 0 && data[len(data)-1] == '\r' {
		return data[0 : len(data)-1]
	}
	return data
}

// ScanLines is a split function for a Scanner that returns each line of
// text, stripped of any trailing end-of-line marker. The returned line may
// be empty. The end-of-line marker is one optional carriage return followed
// by one mandatory newline. In regular expression notation, it is `\r?\n`.
// The last non-empty line of input will be returned even if it has no
// newline.
func ScanLines(data []byte, atEOF bool) (advance int, token []byte, err error) {
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	if i := bytes.IndexByte(data, '\n'); i >= 0 {
		// We have a full newline-terminated line.
		return i + 1, dropCR(data[0:i]), nil
	}
	// If we're at EOF, we have a final, non-terminated line. Return it.
	if atEOF {
		return len(data), dropCR(data), nil
	}
	// Request more data.
	return 0, nil, nil
}

// isSpace reports whether the character is a Unicode white space character.
// We avoid dependency on the unicode package, but check validity of the implementation
// in the tests.
func isSpace(r rune) bool {
	if r <= '\u00FF' {
		// Obvious ASCII ones: \t through \r plus space. Plus two Latin-1 oddballs.
		switch r {
		case ' ', '\t', '\n', '\v', '\f', '\r':
			return true
		case '\u0085', '\u00A0':
			return true
		}
		return false
	}
	// High-valued ones.
	if '\u2000' <= r && r <= '\u200a' {
		return true
	}
	switch r {
	case '\u1680', '\u180e', '\u2028', '\u2029', '\u202f', '\u205f', '\u3000':
		return true
	}
	return false
}

// ScanWords is a split function for a Scanner that returns each
// space-separated word of text, with surrounding spaces deleted. It will
// never return an empty string. The definition of space is set by
// unicode.IsSpace.
func ScanWords(data []byte, atEOF bool) (advance int, token []byte, err error) {
	// Skip leading spaces.
	start := 0
	for width := 0; start < len(data); start += width {
		var r rune
		r, width = utf8.DecodeRune(data[start:])
		if !isSpace(r) {
			break
		}
	}
	if atEOF && len(data) == 0 {
		return 0, nil, nil
	}
	// Scan until space, marking end of word.
	for width, i := 0, start; i < len(data); i += width {
		var r rune
		r, width = utf8.DecodeRune(data[i:])
		if isSpace(r) {
			return i + width, data[start:i], nil
		}
	}
	// If we're at EOF, we have a final, non-empty, non-terminated word. Return it.
	if atEOF && len(data) > start {
		return len(data), data[start:], nil
	}
	// Request more data.
	return 0, nil, nil
}


Your working week consists of $$$n$$$ days numbered from $$$1$$$ to $$$n$$$, after day $$$n$$$ goes day $$$1$$$ again. And $$$3$$$ of them are days off. One of the days off is the last day, day $$$n$$$. You have to decide when the other two are.Choosing days off, you pursue two goals:   No two days should go one after the other. Note that you can't make day $$$1$$$ a day off because it follows day $$$n$$$.  Working segments framed by days off should be as dissimilar as possible in duration. More specifically, if the segments are of size $$$l_1$$$, $$$l_2$$$, and $$$l_3$$$ days long, you want to maximize $$$\min(|l_1 - l_2|, |l_2 - l_3|, |l_3 - l_1|)$$$. Output the maximum value of $$$\min(|l_1 - l_2|, |l_2 - l_3|, |l_3 - l_1|)$$$ that can be obtained.

The first line of the input contains a single integer $$$t$$$ ($$$1 \le t \le 1000$$$) — the number of test cases. The description of test cases follows. The only line of each test case contains the integer $$$n$$$ ($$$6 \le n \le 10^9$$$).

For each test case, output one integer — the maximum possible obtained value.

NoteIn the image below you can see the example solutions for the first two test cases. Chosen days off are shown in purple. Working segments are underlined in green.In test case $$$1$$$, the only options for days off are days $$$2$$$, $$$3$$$, and $$$4$$$ (because $$$1$$$ and $$$5$$$ are next to day $$$n$$$). So the only way to place them without selecting neighboring days is to choose days $$$2$$$ and $$$4$$$. Thus, $$$l_1 = l_2 = l_3 = 1$$$, and the answer $$$\min(|l_1 - l_2|, |l_2 - l_3|, |l_3 - l_1|) = 0$$$.   For test case $$$2$$$, one possible way to choose days off is shown. The working segments have the lengths of $$$2$$$, $$$1$$$, and $$$4$$$ days. So the minimum difference is $$$1 = \min(1, 3, 2) = \min(|2 - 1|, |1 - 4|, |4 - 2|)$$$. It can be shown that there is no way to make it larger.

/*
	A template for Go on codeforces.com
	Author: Yakov, frvr.ru
*/

package main

import (
	"bufio"
	"fmt"
	"os"
	"reflect"
	"strconv"
	"strings"
)

func main() {
	// START WRITING YOUR SOLUTION HERE:
	// writeLine(typeOf(readInt()))
	N := readInt()
	for i := 0; i < N; i += 1 {
		K := readInt()
		// score0 := int(0)

		// l1 := 1
		// for l2 := 1; ; l2 += 1 {
		// 	l3 := K - 3 - l2 - l1
		// 	if l3 < l2 {
		// 		break
		// 	}
		// 	score := score(l1, l2, l3)

		// 	score1 := l2 - 1
		// 	if l2 > (K-3)/3 {
		// 		score1 = K - 4 - 2*l2
		// 	}

		// 	if score != score1 {
		// 		fmt.Println("DEBUG", l2, K, score, score1)
		// 	}

		// 	score0 = max(score, score0)
		// }

		score1 := (K-3)/3 - 1

		// fmt.Println(score0, score1)
		fmt.Println(score1)
	}
}

func score(l1, l2, l3 int) int {
	return min(abs(l2-l1), min(abs(l3-l2), abs(l1-l3)))
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

/* ~~~~~~~~~~ */
/* ~~~~~~~~~~ */
/* ~~~~~~~~~~ */

var in = bufio.NewReader(os.Stdin)

type float = float32
type double = float64
type long = int64
type ulong = uint64

func typeOf(arg interface{}) string {
	switch reflect.TypeOf(arg).Kind() {
	case reflect.Int:
		return "int"
	case reflect.Int8:
		return "int8"
	case reflect.Int16:
		return "int16"
	case reflect.Int32:
		return "int32"
	case reflect.Int64:
		return "int64"
	case reflect.Uint:
		return "uint"
	case reflect.Uint8:
		return "uint8"
	case reflect.Uint16:
		return "uint16"
	case reflect.Uint32:
		return "uint32"
	case reflect.Uint64:
		return "uint64"
	case reflect.Float32:
		return "float32"
	case reflect.Float64:
		return "float64"
	case reflect.Complex64:
		return "complex64"
	case reflect.Complex128:
		return "complex128"
	case reflect.Bool:
		return "bool"
	case reflect.String:
		return "string"
	case reflect.Chan:
		return "chan"
	case reflect.Ptr:
		return "ptr"
	case reflect.Uintptr:
		return "uintptr"
	case reflect.UnsafePointer:
		return "unsafeptr"
	case reflect.Interface:
		return "interface"
	case reflect.Array:
		return "array"
	case reflect.Slice:
		return "slice"
	case reflect.Map:
		return "map"
	case reflect.Struct:
		return "struct"
	case reflect.Func:
		return "func"
	case reflect.Invalid:
		return "invalid"
	default:
		return "nil"
	}
}

/* ~~~~~~~~~~ */

func _scln() string {
	ln, _ := in.ReadString('\n')
	return strings.Trim(ln, " \r\n")
}
func _sc(s []string) string {
	if len(s) == 0 {
		return _scln()
	}
	return s[0]
}

func readLine() string              { return _scln() }
func readString() string            { return _scln() }
func readStrings() []string         { return strings.Split(_scln(), " ") }
func readBool(s ...string) bool     { t, _ := strconv.ParseBool(_sc(s)); return t }
func readByte(s ...string) byte     { t, _ := strconv.ParseUint(_sc(s), 10, 8); return byte(t) }
func readDouble(s ...string) double { t, _ := strconv.ParseFloat(_sc(s), 64); return t }
func readFloat(s ...string) float   { t, _ := strconv.ParseFloat(_sc(s), 32); return float32(t) }
func readInt(s ...string) int       { t, _ := strconv.Atoi(_sc(s)); return t }
func readLong(s ...string) long     { t, _ := strconv.ParseInt(_sc(s), 10, 64); return t }
func readULong(s ...string) ulong   { t, _ := strconv.ParseUint(_sc(s), 10, 64); return t }

/* ~~~~~~~~~~ */

// Too much overhead with universal method using interface{}, wait for the generics,
// but for now — just don't look at the redundancy of the code after that commentary :)

func readBools() []bool {
	strs := readStrings()
	arr := make([]bool, len(strs))
	for i, s := range strs {
		arr[i] = readBool(s)
	}
	return arr
}
func readBytes() []byte {
	strs := readStrings()
	arr := make([]byte, len(strs))
	for i, s := range strs {
		arr[i] = readByte(s)
	}
	return arr
}
func readDoubles() []double {
	strs := readStrings()
	arr := make([]double, len(strs))
	for i, s := range strs {
		arr[i] = readDouble(s)
	}
	return arr
}
func readFloats() []float {
	strs := readStrings()
	arr := make([]float, len(strs))
	for i, s := range strs {
		arr[i] = readFloat(s)
	}
	return arr
}
func readInts() []int {
	strs := readStrings()
	arr := make([]int, len(strs))
	for i, s := range strs {
		arr[i] = readInt(s)
	}
	return arr
}
func readLongs() []long {
	strs := readStrings()
	arr := make([]long, len(strs))
	for i, s := range strs {
		arr[i] = readLong(s)
	}
	return arr
}
func readULongs() []ulong {
	strs := readStrings()
	arr := make([]ulong, len(strs))
	for i, s := range strs {
		arr[i] = readULong(s)
	}
	return arr
}

/* ~~~~~~~~~~ */

func write(arg ...interface{})                 { fmt.Print(arg...) }
func writeLine(arg ...interface{})             { fmt.Println(arg...) }
func writeFormat(f string, arg ...interface{}) { fmt.Printf(f, arg...) }

package main

import (
	"bufio"
	"fmt"
	"os"
)

var (
	writer  = bufio.NewWriter(os.Stdout)
	scanner = bufio.NewScanner(os.Stdin)
)

func init() {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 4096), 1e9)
}

func printf(f string, a ...interface{}) {
	fmt.Fprintf(writer, f, a...)
}

func _int() int {
	s := _string()
	i := 0
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int(r - '0')
	}
	return i
}

func _int64() int64 {
	s := _string()
	i := int64(0)
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int64(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int64(r - '0')
	}
	return i
}

func _string() string {
	if !scanner.Scan() {
		panic(scanner.Err())
	}
	return scanner.Text()
}

func main() {
	defer writer.Flush()
	for t := _int(); t > 0; t-- {
		n := _int()
		printf("%d\n", n/3-2)
	}
}

package main
// github.com/jamesgrimard/codeforces
import(
    "fmt"
    "bufio"
    "os"
)
func main() {
	in:= bufio.NewReader(os.Stdin)
	out:= bufio.NewWriter(os.Stdout)
	defer out.Flush()
	var t int
	fmt.Fscan(in,&t)
	for i:=0;i<t;i++{
		var n int
		fmt.Fscan(in,&n)
		var a,b,c int
		a = 1
		if (n - 3) % 3 == 0 {
			b = (n - 3) / 3
		} else {
			b = (n - 3) / 3 * 2
		}
		c = n - 3 - (a + b)
		fmt.Fprintln(out,min(abs(a-b),abs(b-c),abs(a-c)))
	}
}
func abs(a int) int {
	if a < 0 {
		return a * -1
	}
	return a
}

func min(a,b,c int) int {
	if a <= b && a <= c {
		return a
	} else if b <= a && b <= c {
		return b
	}
	return c
}

package main

import (
	. "fmt"
)

var t int

func max(a, b int64) int64 {
	if a > b {
		return a
	}
	return b
}

func main() {

	Scan(&t)
	for i := 0; i < t; i++ {
		var n int64
		Scan(&n)
		Println(max(0, (n-6)/3))
	}
}

package main

import (
	"fmt"
)

func main() {
	var tests int
	fmt.Scan(&tests)
	for i := 0; i < tests; i++ {
		var n int
		fmt.Scan(&n)
		fmt.Println((n - 6) / 3)
	}
}

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var T int
	fmt.Fscan(in, &T)
	for t := 0; t < T; t++ {
		var n int
		fmt.Fscan(in, &n)

		d := int(math.Floor(float64(n) / 3))
		a := d - 1
		// b := d*2 - d - 1
		// c := n - d*2 - 1

		fmt.Fprintln(out, a-1)
	}
}

package main

import "fmt"

func main() {
	round := 0
	fmt.Scanf("%d\n", &round)
	for i := 0; i < round; i++ {
		input := 0
		fmt.Scanf("%d\n", &input)
		num1, num2, num3 := 0, 0, 0
		num2 = (input - 3) / 3
		num1 = 1
		num3 = input - num2 - num1
		fmt.Println(min(num3-num2, num2-num1))
	}
	return
}

func min(a, b int) int {
	if a > b {
		return b
	}
	return a
}

package main

import "fmt"

func main() {
	var n int
	fmt.Scanf("%d\n", &n)
	for i := 0; i < n; i++ {
		var k int
		fmt.Scanf("%d\n", &k)
		fmt.Printf("%d\n", (k-6)/3)
	}
}

package main

import (
	"bufio"
	"fmt"
	"os"
)

var reader *bufio.Reader = bufio.NewReader(os.Stdin)
var writer *bufio.Writer = bufio.NewWriter(os.Stdout)

func scanf(format string, args ...interface{})  { fmt.Fscanf(reader, format, args...) }
func printf(format string, args ...interface{}) { fmt.Fprintf(writer, format, args...) }

func main() {
	defer writer.Flush()

	var t int
	scanf("%d\n", &t)
	for i := 0; i < t; i++ {
		var n int64
		scanf("%d\n", &n)
		answer(n)
	}
}

func answer(n int64) {
	total := n - 3
	ans := (total / 3) - 1

	printf("%d\n", ans)
}

package main

import (
	"bufio"
	"fmt"
	"os"
)

var (
	in  = bufio.NewReader(os.Stdin)
	out = bufio.NewWriter(os.Stdout)
)

func scan(a ...interface{}) {
	fmt.Fscan(in, a...)
}
func printf(f string, a ...interface{}) {
	fmt.Fprintf(out, f, a...)
}

func solve() {
	var n int
	scan(&n)
	printf("%d\n", int(n/3)-2)
}
func main() {
	defer out.Flush()
	n := 0
	scan(&n)
	for i := 0; i < n; i++ {
		solve()
	}
}

package main

import "fmt"

func main() {
	var t int
	var n int64
	var outputArr [1000]int64
	_, err := fmt.Scanln(&t)
	if err != nil {
		fmt.Println(err)
	}
	for i := 0; i < t; i++ {
		_, err2 := fmt.Scanln(&n)
		if err2 != nil {
			fmt.Println(err2)
		}
		result := n/3 - 2
		outputArr[i] = result
	}
	for j := 0; j < t; j++ {
		fmt.Println(outputArr[j])
	}
}

package main

import (
	"bufio"
	"fmt"
	"os"
)

func abs(x int) int {
	if x < 0 {
		return -x
	}
	return x
}

func main() {
	r := bufio.NewReader(os.Stdin)
	w := bufio.NewWriter(os.Stdout)
	defer w.Flush()

	var T, n int
	fmt.Fscan(r, &T)

	for i := 0; i < T; i++ {
		fmt.Fscan(r, &n)
		x := (n - 3) / 3
		y := n - 4 -x

		if abs(x - 1) > abs(y - x) {
			fmt.Fprintln(w, abs(y - x))
		} else {
			fmt.Fprintln(w, x - 1)
		}
	}
}

package main

import (
	"bufio"
	"fmt"
	"os"
)

var in, out = bufio.NewReader(os.Stdin), bufio.NewWriter(os.Stdout)

func main() {
	defer out.Flush()

	var tc, n int
	for fmt.Fscan(in, &tc); tc > 0; tc-- {
		fmt.Fscan(in, &n)
		lo, hi := 0, n
		for lo <= hi {
			m := (lo + hi) / 2
			if 1 + (m+1) + (2*m+1) <= n-3 {
				lo = m+1
			} else {
				hi = m-1
			}
		}
		fmt.Println(hi)
	}
}

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
)

const cf = true

func solve() {
	var n int
	fmt.Fscan(in, &n)
	fmt.Fprintln(out, (n-3)/3-1)
}

func main() {
	defer out.Flush()
	t := 1
	fmt.Fscan(in, &t)
	for ; t > 0; t-- {
		solve()
	}
}

func ConvertInt(val string, base, toBase int) (string, error) {
	i, err := strconv.ParseInt(val, base, 64)
	if err != nil {
		return "", err
	}
	return strconv.FormatInt(i, toBase), nil
}

type set[T Ordered] struct {
	itms map[T]struct{}
}

func (s *set[T]) init() {
	if s.itms == nil {
		s.itms = make(map[T]struct{})
	}
}

func (s *set[T]) add(item T) *set[T] {
	s.init()
	s.itms[item] = exists
	return s
}

func (s *set[T]) remove(item T) *set[T] {
	s.init()
	delete(s.itms, item)
	return s
}

func (s *set[T]) has(item T) bool {
	s.init()
	_, c := s.itms[item]
	return c
}

func (s *set[T]) sortedItems() []T {
	s.init()
	items := make([]T, 0, s.size())
	for item := range s.itms {
		items = append(items, item)
	}
	sort.Slice(items, func(i, j int) bool {
		return items[i] < items[j]
	})
	return items
}

func (s *set[T]) items() []T {
	s.init()
	items := make([]T, 0, s.size())
	for item := range s.itms {
		items = append(items, item)
	}
	return items
}

func (s *set[T]) size() int {
	s.init()
	return len(s.itms)
}

var exists = struct{}{}

const MaxUint = ^uint(0)
const MinUint = 0
const MaxInt = int(MaxUint >> 1)
const MinInt = -MaxInt - 1

func reverseStr(s string) string {
	r := []rune(s)
	for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
		r[i], r[j] = r[j], r[i]
	}
	return string(r)
}

type Float interface {
	~float32 | ~float64
}

type Integer interface {
	Signed | Unsigned
}

type Signed interface {
	~int | ~int8 | ~int16 | ~int32 | ~int64
}

type Unsigned interface {
	~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
}

type Ordered interface {
	Integer | Float | ~string
}

func abs[T Signed](x T) T {
	if x < 0 {
		return -x
	}
	return x
}

func min[T Ordered](x, y T) T {
	if x < y {
		return x
	}
	return y
}

func max[T Ordered](x, y T) T {
	if x > y {
		return x
	}
	return y
}

var (
	in  = getReader()
	out = getWriter()
)

func getReader() *bufio.Reader {
	if cf {
		return bufio.NewReader(os.Stdin)
	} else {
		in, _ := os.Open("input.txt")
		return bufio.NewReader(in)
	}
}

func getWriter() *bufio.Writer {
	if cf {
		return bufio.NewWriter(os.Stdout)
	} else {
		out, _ := os.Create("output.txt")
		return bufio.NewWriter(out)
	}
}

/*
	A template for Go on codeforces.com
	Author: Yakov, frvr.ru
*/

package main

import (
	"bufio"
	"fmt"
	"os"
	"reflect"
	"strconv"
	"strings"
)

func main() {
	// START WRITING YOUR SOLUTION HERE:
	// writeLine(typeOf(readInt()))
	N := readInt()
	for i := 0; i < N; i += 1 {
		K := readInt()
		score0 := int(0)

		l1 := 1
		for l2 := 1; ; l2 += 1 {
			l3 := K - 3 - l2
			if l3 < l2 {
				break
			}
			score := score(l1, l2, l3)
			score0 = max(score, score0)
		}

		fmt.Println(score0)
	}
}

func score(l1, l2, l3 int) int {
	return min(abs(l2-l1), min(abs(l3-l2), abs(l1-l3)))
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

/* ~~~~~~~~~~ */
/* ~~~~~~~~~~ */
/* ~~~~~~~~~~ */

var in = bufio.NewReader(os.Stdin)

type float = float32
type double = float64
type long = int64
type ulong = uint64

func typeOf(arg interface{}) string {
	switch reflect.TypeOf(arg).Kind() {
	case reflect.Int:
		return "int"
	case reflect.Int8:
		return "int8"
	case reflect.Int16:
		return "int16"
	case reflect.Int32:
		return "int32"
	case reflect.Int64:
		return "int64"
	case reflect.Uint:
		return "uint"
	case reflect.Uint8:
		return "uint8"
	case reflect.Uint16:
		return "uint16"
	case reflect.Uint32:
		return "uint32"
	case reflect.Uint64:
		return "uint64"
	case reflect.Float32:
		return "float32"
	case reflect.Float64:
		return "float64"
	case reflect.Complex64:
		return "complex64"
	case reflect.Complex128:
		return "complex128"
	case reflect.Bool:
		return "bool"
	case reflect.String:
		return "string"
	case reflect.Chan:
		return "chan"
	case reflect.Ptr:
		return "ptr"
	case reflect.Uintptr:
		return "uintptr"
	case reflect.UnsafePointer:
		return "unsafeptr"
	case reflect.Interface:
		return "interface"
	case reflect.Array:
		return "array"
	case reflect.Slice:
		return "slice"
	case reflect.Map:
		return "map"
	case reflect.Struct:
		return "struct"
	case reflect.Func:
		return "func"
	case reflect.Invalid:
		return "invalid"
	default:
		return "nil"
	}
}

/* ~~~~~~~~~~ */

func _scln() string {
	ln, _ := in.ReadString('\n')
	return strings.Trim(ln, " \r\n")
}
func _sc(s []string) string {
	if len(s) == 0 {
		return _scln()
	}
	return s[0]
}

func readLine() string              { return _scln() }
func readString() string            { return _scln() }
func readStrings() []string         { return strings.Split(_scln(), " ") }
func readBool(s ...string) bool     { t, _ := strconv.ParseBool(_sc(s)); return t }
func readByte(s ...string) byte     { t, _ := strconv.ParseUint(_sc(s), 10, 8); return byte(t) }
func readDouble(s ...string) double { t, _ := strconv.ParseFloat(_sc(s), 64); return t }
func readFloat(s ...string) float   { t, _ := strconv.ParseFloat(_sc(s), 32); return float32(t) }
func readInt(s ...string) int       { t, _ := strconv.Atoi(_sc(s)); return t }
func readLong(s ...string) long     { t, _ := strconv.ParseInt(_sc(s), 10, 64); return t }
func readULong(s ...string) ulong   { t, _ := strconv.ParseUint(_sc(s), 10, 64); return t }

/* ~~~~~~~~~~ */

// Too much overhead with universal method using interface{}, wait for the generics,
// but for now — just don't look at the redundancy of the code after that commentary :)

func readBools() []bool {
	strs := readStrings()
	arr := make([]bool, len(strs))
	for i, s := range strs {
		arr[i] = readBool(s)
	}
	return arr
}
func readBytes() []byte {
	strs := readStrings()
	arr := make([]byte, len(strs))
	for i, s := range strs {
		arr[i] = readByte(s)
	}
	return arr
}
func readDoubles() []double {
	strs := readStrings()
	arr := make([]double, len(strs))
	for i, s := range strs {
		arr[i] = readDouble(s)
	}
	return arr
}
func readFloats() []float {
	strs := readStrings()
	arr := make([]float, len(strs))
	for i, s := range strs {
		arr[i] = readFloat(s)
	}
	return arr
}
func readInts() []int {
	strs := readStrings()
	arr := make([]int, len(strs))
	for i, s := range strs {
		arr[i] = readInt(s)
	}
	return arr
}
func readLongs() []long {
	strs := readStrings()
	arr := make([]long, len(strs))
	for i, s := range strs {
		arr[i] = readLong(s)
	}
	return arr
}
func readULongs() []ulong {
	strs := readStrings()
	arr := make([]ulong, len(strs))
	for i, s := range strs {
		arr[i] = readULong(s)
	}
	return arr
}

/* ~~~~~~~~~~ */

func write(arg ...interface{})                 { fmt.Print(arg...) }
func writeLine(arg ...interface{})             { fmt.Println(arg...) }
func writeFormat(f string, arg ...interface{}) { fmt.Printf(f, arg...) }

/*
	A template for Go on codeforces.com
	Author: Yakov, frvr.ru
*/

package main

import (
	"bufio"
	"fmt"
	"os"
	"reflect"
	"strconv"
	"strings"
)

func main() {
	// START WRITING YOUR SOLUTION HERE:
	// writeLine(typeOf(readInt()))
	N := readInt()
	for i := 0; i < N; i += 1 {
		K := readInt()
		score0 := int(0)

		l1 := 1
		for l2 := 2; ; l2 += 1 {
			l3 := K - 3 - l2
			if l3 <= l2 {
				break
			}
			score := min(abs(l2-l1), min(abs(l3-l2), abs(l1-l3)))
			score0 = max(score, score0)
		}

		fmt.Println(score0)
	}
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

func abs(a int) int {
	if a < 0 {
		return -a
	}
	return a
}

/* ~~~~~~~~~~ */
/* ~~~~~~~~~~ */
/* ~~~~~~~~~~ */

var in = bufio.NewReader(os.Stdin)

type float = float32
type double = float64
type long = int64
type ulong = uint64

func typeOf(arg interface{}) string {
	switch reflect.TypeOf(arg).Kind() {
	case reflect.Int:
		return "int"
	case reflect.Int8:
		return "int8"
	case reflect.Int16:
		return "int16"
	case reflect.Int32:
		return "int32"
	case reflect.Int64:
		return "int64"
	case reflect.Uint:
		return "uint"
	case reflect.Uint8:
		return "uint8"
	case reflect.Uint16:
		return "uint16"
	case reflect.Uint32:
		return "uint32"
	case reflect.Uint64:
		return "uint64"
	case reflect.Float32:
		return "float32"
	case reflect.Float64:
		return "float64"
	case reflect.Complex64:
		return "complex64"
	case reflect.Complex128:
		return "complex128"
	case reflect.Bool:
		return "bool"
	case reflect.String:
		return "string"
	case reflect.Chan:
		return "chan"
	case reflect.Ptr:
		return "ptr"
	case reflect.Uintptr:
		return "uintptr"
	case reflect.UnsafePointer:
		return "unsafeptr"
	case reflect.Interface:
		return "interface"
	case reflect.Array:
		return "array"
	case reflect.Slice:
		return "slice"
	case reflect.Map:
		return "map"
	case reflect.Struct:
		return "struct"
	case reflect.Func:
		return "func"
	case reflect.Invalid:
		return "invalid"
	default:
		return "nil"
	}
}

/* ~~~~~~~~~~ */

func _scln() string {
	ln, _ := in.ReadString('\n')
	return strings.Trim(ln, " \r\n")
}
func _sc(s []string) string {
	if len(s) == 0 {
		return _scln()
	}
	return s[0]
}

func readLine() string              { return _scln() }
func readString() string            { return _scln() }
func readStrings() []string         { return strings.Split(_scln(), " ") }
func readBool(s ...string) bool     { t, _ := strconv.ParseBool(_sc(s)); return t }
func readByte(s ...string) byte     { t, _ := strconv.ParseUint(_sc(s), 10, 8); return byte(t) }
func readDouble(s ...string) double { t, _ := strconv.ParseFloat(_sc(s), 64); return t }
func readFloat(s ...string) float   { t, _ := strconv.ParseFloat(_sc(s), 32); return float32(t) }
func readInt(s ...string) int       { t, _ := strconv.Atoi(_sc(s)); return t }
func readLong(s ...string) long     { t, _ := strconv.ParseInt(_sc(s), 10, 64); return t }
func readULong(s ...string) ulong   { t, _ := strconv.ParseUint(_sc(s), 10, 64); return t }

/* ~~~~~~~~~~ */

// Too much overhead with universal method using interface{}, wait for the generics,
// but for now — just don't look at the redundancy of the code after that commentary :)

func readBools() []bool {
	strs := readStrings()
	arr := make([]bool, len(strs))
	for i, s := range strs {
		arr[i] = readBool(s)
	}
	return arr
}
func readBytes() []byte {
	strs := readStrings()
	arr := make([]byte, len(strs))
	for i, s := range strs {
		arr[i] = readByte(s)
	}
	return arr
}
func readDoubles() []double {
	strs := readStrings()
	arr := make([]double, len(strs))
	for i, s := range strs {
		arr[i] = readDouble(s)
	}
	return arr
}
func readFloats() []float {
	strs := readStrings()
	arr := make([]float, len(strs))
	for i, s := range strs {
		arr[i] = readFloat(s)
	}
	return arr
}
func readInts() []int {
	strs := readStrings()
	arr := make([]int, len(strs))
	for i, s := range strs {
		arr[i] = readInt(s)
	}
	return arr
}
func readLongs() []long {
	strs := readStrings()
	arr := make([]long, len(strs))
	for i, s := range strs {
		arr[i] = readLong(s)
	}
	return arr
}
func readULongs() []ulong {
	strs := readStrings()
	arr := make([]ulong, len(strs))
	for i, s := range strs {
		arr[i] = readULong(s)
	}
	return arr
}

/* ~~~~~~~~~~ */

func write(arg ...interface{})                 { fmt.Print(arg...) }
func writeLine(arg ...interface{})             { fmt.Println(arg...) }
func writeFormat(f string, arg ...interface{}) { fmt.Printf(f, arg...) }

package main

import (
	"bufio"
	"fmt"
	"os"
)

var (
	writer  = bufio.NewWriter(os.Stdout)
	scanner = bufio.NewScanner(os.Stdin)
)

func init() {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 4096), 1e9)
}

func printf(f string, a ...interface{}) {
	fmt.Fprintf(writer, f, a...)
}

func _int() int {
	s := _string()
	i := 0
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int(r - '0')
	}
	return i
}

func _int64() int64 {
	s := _string()
	i := int64(0)
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int64(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int64(r - '0')
	}
	return i
}

func _string() string {
	if !scanner.Scan() {
		panic(scanner.Err())
	}
	return scanner.Text()
}

func main() {
	defer writer.Flush()
	for t := _int(); t > 0; t-- {
		n := _int()
		printf("%d\n", sol(n))
	}
}

func sol(n int) int {
	s := n - 4
	u := s / 3
	l1 := 1
	l2 := u
	l3 := s - u
	return min(l2-l1, l3-l2)
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

package main

import (
	"bufio"
	"fmt"
	"os"
)

var (
	writer  = bufio.NewWriter(os.Stdout)
	scanner = bufio.NewScanner(os.Stdin)
)

func init() {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 4096), 1e9)
}

func printf(f string, a ...interface{}) {
	fmt.Fprintf(writer, f, a...)
}

func _int() int {
	s := _string()
	i := 0
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int(r - '0')
	}
	return i
}

func _int64() int64 {
	s := _string()
	i := int64(0)
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int64(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int64(r - '0')
	}
	return i
}

func _string() string {
	if !scanner.Scan() {
		panic(scanner.Err())
	}
	return scanner.Text()
}

func main() {
	defer writer.Flush()
	for t := _int(); t > 0; t-- {
		n := _int()
		printf("%d\n", sol(n))
	}
}

func sol(n int) int {
	s := n - 4
	u := s / 3
	l1 := 1
	l2 := l1 + u
	l3 := 1 + s - u
	return min(l2-l1, l3-l2)
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

package main

import (
	"bufio"
	"fmt"
	"os"
)

var (
	writer  = bufio.NewWriter(os.Stdout)
	scanner = bufio.NewScanner(os.Stdin)
)

func init() {
	scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 4096), 1e9)
}

func printf(f string, a ...interface{}) {
	fmt.Fprintf(writer, f, a...)
}

func _int() int {
	s := _string()
	i := 0
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int(r - '0')
	}
	return i
}

func _int64() int64 {
	s := _string()
	i := int64(0)
	if s[0] == '-' {
		for _, r := range s[1:] {
			i *= 10
			i -= int64(r - '0')
		}
		return i
	}
	for _, r := range s {
		i *= 10
		i += int64(r - '0')
	}
	return i
}

func _string() string {
	if !scanner.Scan() {
		panic(scanner.Err())
	}
	return scanner.Text()
}

func main() {
	defer writer.Flush()
	for t := _int(); t > 0; t-- {
		n := _int()
		printf("%d\n", sol(n))
	}
}

func sol(n int) int {
	if n == 6 {
		return 0
	}
	s := n - 4
	u := s / 3
	l1 := 1
	l2 := l1 + u
	l3 := s - u
	return min(l2-l1, l3-l2)
}

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

package main
// github.com/jamesgrimard/codeforces
import(
    "fmt"
    "bufio"
    "os"
)
func main() {
	in:= bufio.NewReader(os.Stdin)
	out:= bufio.NewWriter(os.Stdout)
	defer out.Flush()
	var t int
	fmt.Fscan(in,&t)
	for i:=0;i<t;i++{
		var n int
		fmt.Fscan(in,&n)
		var a,b,c int
		a = 1
		b = (n - 3) / 3 * 2
		c = n - 3 - (a + b)
		if n == 6 {
			fmt.Fprintln(out,0)
		} else {
			fmt.Fprintln(out,min(abs(a-b),abs(b-c),abs(a-c)))
		}
	}
}
func abs(a int) int {
	if a < 0 {
		return a * -1
	}
	return a
}

func min(a,b,c int) int {
	if a <= b && a <= c {
		return a
	} else if b <= a && b <= c {
		return b
	}
	return c
}

package main
// github.com/jamesgrimard/codeforces
import(
    "fmt"
    "bufio"
    "os"
)
func main() {
	in:= bufio.NewReader(os.Stdin)
	out:= bufio.NewWriter(os.Stdout)
	defer out.Flush()
	var t int
	fmt.Fscan(in,&t)
	for i:=0;i<t;i++{
		var n int
		fmt.Fscan(in,&n)
		var a,b,c int
		a = 1
		b = (n - 3) / 3 * 2
		c = n - 3 - (a + b)
		fmt.Fprintln(out,min(abs(a-b),abs(b-c),abs(a-c)))
	}
}
func abs(a int) int {
	if a < 0 {
		return a * -1
	}
	return a
}

func min(a,b,c int) int {
	if a <= b && a <= c {
		return a
	} else if b <= a && b <= c {
		return b
	}
	return c
}

package main

import (
    ."fmt"
)

func max(a, b int64) int64{
    if a > b {
        return a
    }
    return b
}

func main(){

    var n int64

    Scan(&n)

    Println(max(0, (n - 6) / 3))
}

package main

import (
	"fmt"
)

func main() {
	var tests int
	fmt.Scan(&tests)
	for i := 0; i < tests; i++ {
		var n int
		fmt.Scan(&n)
		fmt.Println((n - 7) / 3)
	}
}

package main

import (
	"bufio"
	"fmt"
	"math"
	"os"
)

func main() {
	in := bufio.NewReader(os.Stdin)
	out := bufio.NewWriter(os.Stdout)
	defer out.Flush()

	var T int
	fmt.Fscan(in, &T)
	for t := 0; t < T; t++ {
		var n float64
		fmt.Fscan(in, &n)

		fmt.Fprintln(out, math.Floor(n/3)-2)
	}
}