#include <bits/stdc++.h>
using namespace std;
bool prime[5000];
int ans[3010];
int n, cnt;
void make_prime() {
  for (int i = 2; i < 3050; i++) {
    if (prime[i] == false)
      for (int j = i + i; j < 3050; j += i) {
        prime[j] = true;
      }
  }
}
int main() {
  cin >> n;
  make_prime();
  for (int i = 2; i <= n; i++) {
    for (int j = 2; j < i; j++) {
      if (prime[j] == false) {
        if (i % j == 0) {
          ans[i]++;
        }
      }
    }
  }
  for (int i = 2; i <= n; i++) {
    if (ans[i] == 2) cnt++;
  }
  cout << cnt << endl;
}
