#include <cstdio>
#include <iostream>
using namespace std;

int main()
{
  int n;
  int cou1, cou2;
  while (scanf("%d", &n) != EOF){
    cou2 = 0;
    for (int i = 2; i <= n; i++){
      cou1 = 0;

      for (int j = 1; j <= n; j++){

        if (i % j == 0){
          cou1++;
        }
      }
      if (cou1 == 2){
        cou2++;
      }
    }
    cout << cou2 << "\n";
  }

  return 0;
}