#include <bits/stdc++.h>
using namespace std;
int a[10001], n, i, j, c;
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) c++;
  }
  cout << c;
  return 0;
}
