#include <bits/stdc++.h>
using namespace std;
int a, b[3001] = {0, 1}, s;
int main() {
  cin >> a;
  for (int i = 1; i <= a; i++)
    if (i >= 2)
      if (b[i] == 0) {
        for (int j = 2; j * i <= a; j++) b[i * j]++;
      } else if (b[i] == 2)
        s++;
  cout << s;
  return 0;
}
