#include <cstdio>

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++)
  {
    divisors = 0;
    for(y=1; y<=x; y++)
    {
      if(x%y == 0)
      {
        divisors++;
      }
    }
    if(divisors == 2) {
      ttl++;
    }
  }
  printf("%d\n", ttl);
  return 0;
}