#include <bits/stdc++.h>
using namespace std;
int m, n;
int main() {
  scanf("%d", &n);
  m = 0;
  for (int i = 1; i <= n; i++) {
    int j = i, s = 0;
    for (int k = 2; k <= j; k++) {
      if (j % k == 0) {
        s++;
        while (j % k == 0) {
          j /= k;
        }
      }
    }
    m += int(s == 2);
  }
  printf("%d\n", m);
  return 0;
}
