#include <bits/stdc++.h>
using namespace std;
int n;
bool primes[100000];
void sieve() {
  for (long long p = 2; p <= 100000; ++p) {
    if (primes[p] == false) {
      for (int k = 2; k * p <= 100000; ++k) {
        primes[k * p] = true;
      }
    }
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  sieve();
  cin >> n;
  int cnt = 0, answ = 0;
  if (n < 6) {
    cout << "0"
         << "\n";
    return 0;
  } else {
    for (int i = 6; i <= n; i++) {
      cnt = 0;
      for (int j = 2; j < n; j++) {
        if (i % j == 0 && !primes[j]) {
          cnt++;
        }
      }
      if (cnt == 2) answ++;
    }
  }
  cout << answ << "\n";
  return 0;
}
