#include <bits/stdc++.h>
using namespace std;
int a[5000];
int main() {
  int n, res = 0;
  int i, j;
  scanf("%d", &n);
  for (i = 2; i <= n; i++) {
    for (j = 2; j < i; j++) {
      if (a[j] == 0 && i % j == 0) a[i]++;
    }
    if (a[i] == 2) {
      res++;
    }
  }
  printf("%d\n", res);
  return 0;
}
