#include <bits/stdc++.h>
using namespace std;
bool check(int a) {
  int cnt = 0;
  for (int i = 2; i * i <= a; i++) {
    if (a % i == 0) {
      cnt++;
      for (; a % i == 0; a /= i)
        ;
    }
  }
  if (a != 1) cnt++;
  return cnt == 2;
}
int main() {
  int n;
  cin >> n;
  int ans = 0;
  for (int i = 1; i <= n; i++) {
    if (check(i)) {
      ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
