#include <bits/stdc++.h>
using namespace std;
int a[100001], i, j, k, n;
int main() {
  cin >> n;
  for (i = 2; i <= n; i++) {
    if (a[i] == 0)
      for (j = i; j <= n; j += i) a[j]++;
    if (a[i] == 2) k++;
  }
  cout << k;
}
