#include <cstdio>

char A[20000005];
int main()
{
  freopen("ciur.in", "r", stdin);
  freopen("ciur.out", "w", stdout);

  int divisors, ttl;
  long T, x, y;
  scanf("%ld", &T);

  for(x=2; x<=T; x++)
  {
    for(y=2; x*y <= T; y++)
    {
      A[x*y]=1;
    }
  }

  for(x=2; x<=T;x++)
  {
    //printf("x: %ld: %d\n", x, A[x]);
    if(A[x] == 1)
    {
      ttl++;
    }
  }

  printf("%ld\n", T-ttl-1);
  return 0;
}