#include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
int check_prime(int n) {
  int ans = 0, i;
  if (n % 2 == 0) ans++;
  while (n % 2 == 0) n /= 2;
  for (i = 3; i <= n; i += 2) {
    if (n % i == 0) {
      ans++;
      while (n % i == 0) n /= i;
    }
  }
  if (ans == 2)
    return 1;
  else
    return 0;
}
int main() {
  int n;
  cin >> n;
  int i, an = 0;
  for (i = 6; i < n + 1; i++) {
    an += check_prime(i);
  }
  cout << an;
  return 0;
}
