#include <bits/stdc++.h>
using namespace std;
const int MAXn = 3000 + 10;
int n, arr[MAXn], ans;
int main() {
  cin >> n;
  for (int i = 2; i <= n; i++) {
    if (arr[i] == 2) ans++;
    if (arr[i] != 0) continue;
    for (int j = 2; i * j <= n; j++) arr[i * j]++;
  }
  cout << ans << endl;
  return 0;
}
