#include <bits/stdc++.h>
using namespace std;
int almostPrime(int n) {
  int cont = 0;
  for (int i = 2; i <= (int)sqrt(n); ++i) {
    if (n % i == 0) {
      cont++;
      while (n % i == 0) {
        n /= i;
      }
    }
  }
  if (n != 1) {
    cont++;
  }
  return cont;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.precision(10);
  cout << fixed;
  int n;
  cin >> n;
  int cont = 0;
  for (int i = 6; i <= n; i++) {
    if (almostPrime(i) == 2) {
      cont++;
    }
  }
  cout << cont;
  return 0;
}
