#include <iostream>
using namespace std;

int main()
{
  int i, j;
  int n;
  int ans;
  int count;

  ans = 0;

  cin >> n;
  for (i = 2; i <= n; i++){
    count = 0;
    for (j = 1; j <= i; j++){
      if (i % j == 0){
        count++;
      }
    }

    if (count == 2){
      ans++;
    }
  }
  cout << ans << "\n";

  return (0);
}