






from math import factorial
def        UpperCAmelCase      (   _lowercase,      _lowercase      ):


    '''simple docstring'''



    return factorial(lowercase_      ) / (factorial(lowercase_      ) * factorial(n - r      ))
def        UpperCAmelCase      (   ):


    '''simple docstring'''



    _lowercase     =	0

    for i in range(1,      101      ):
        for j in range(1,      i + 1      ):
            if combinations(lowercase_,      lowercase_      ) > 1e6:
                total += 1
    return total


if __name__ == "__main__":
   print(solution())








from __future__ import annotations
def        UpperCAmelCase      (   _lowercase      ):


    '''simple docstring'''



    global graph, reversed_graph, scc, component, visit, stack
    if visit[u]:
        return
    _lowercase     =	True
    for v in graph[u]:
        dfs(_lowercase      )
    stack.append(_lowercase      )
def        UpperCAmelCase      (   _lowercase      ):


    '''simple docstring'''



    global graph, reversed_graph, scc, component, visit, stack
    if visit[u]:
        return
    _lowercase     =	True
    component.append(_lowercase      )
    for v in reversed_graph[u]:
        dfsa(_lowercase      )
def        UpperCAmelCase      (   ):


    '''simple docstring'''



    global graph, reversed_graph, scc, component, visit, stack
    for i in range(_lowercase      ):
        dfs(_lowercase      )
    _lowercase     =	[False] * n
    for i in stack[::-1]:
        if visit[i]:
            continue
        _lowercase     =	[]
        dfsa(_lowercase      )
        scc.append(_lowercase      )
    return scc


if __name__ == "__main__":
   # n - no of nodes, m - no of edges
   lowerCamelCase						,		lowerCamelCase										=  list(map(int, input().strip().split()))

   lowerCamelCase										=  [[] for _ in range(n)]  # graph
   lowerCamelCase										=  [[] for i in range(n)]  # reversed graph
   # input graph data (edges)
   for _ in range(m):
      lowerCamelCase						,		lowerCamelCase										=  list(map(int, input().strip().split()))
      graph[u].append(v)
      reversed_graph[v].append(u)

   lowerCamelCase										=  []
   lowerCamelCase										=  [False] * n
   lowerCamelCase										=  []
   lowerCamelCase										=  []
   print(kosaraju())
