#include <bits/stdc++.h>
using namespace std;
int main() {
  int maxno;
  cin >> maxno;
  int ans = 0;
  for (int a = 2; a <= maxno; a++) {
    int n = a;
    int i = 0;
    vector<int> res;
    for (int i = 2; i * i <= n; i++) {
      if (n % i == 0) {
        res.push_back(i);
        while (n % i == 0) {
          n = n / i;
        }
      }
    }
    if (n != 1) res.push_back(n);
    if (res.size() == 2) ans++;
  }
  cout << ans;
}
