#include <bits/stdc++.h>
using namespace std;
int n;
bool is_s(int a) {
  int t = sqrt((double)a) + 1;
  if (a == 2) return true;
  for (int i = 2; i <= t; i++)
    if (a % i == 0) return false;
  return true;
}
bool check(int a) {
  int cnt = 0;
  for (int i = 2; i < a; i++)
    if (is_s(i) && a % i == 0) cnt++;
  return cnt == 2;
}
int main() {
  int cnt = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) cnt += check(i);
  cout << cnt;
  return 0;
}
