#include <bits/stdc++.h>
using namespace std;
int n;
int i, j, s;
int mass[3001];
int main() {
  cin >> n;
  i = 1;
  while (i <= n) {
    mass[i] = 0;
    i = i + 1;
  }
  s = 0;
  i = 2;
  while (i <= n) {
    if (mass[i] == 0) {
      j = i;
      while (j <= n) {
        mass[j] = mass[j] + 1;
        j = j + i;
      }
    }
    if (mass[i] == 2) {
      s = s + 1;
    }
    i = i + 1;
  }
  cout << s;
  return 0;
}
