#include <bits/stdc++.h>
using namespace std;
int A[5005];
int main() {
  int n, ans = 0;
  cin >> n;
  for (int i = 2; i <= n; i++) {
    for (int j = 2; j < i; j++) {
      if (A[j] == 0 && i % j == 0) A[i]++;
    }
    if (A[i] == 2) ans++;
  }
  cout << ans << endl;
  return 0;
}
