#include <bits/stdc++.h>
using namespace std;
bool check(int x) {
  int len = sqrt((double)x);
  int cnt = 0;
  for (int i = 2; i <= len; i++) {
    if (x % i == 0) {
      while (x % i == 0) x /= i;
      cnt++;
    }
  }
  if (x > 1) cnt++;
  return cnt == 2;
}
int main() {
  int n;
  scanf("%d", &n);
  int ans = 0;
  for (int i = 2; i <= n; i++) {
    if (check(i)) ans++;
  }
  printf("%d\n", ans);
}
