#include <bits/stdc++.h>
long long ar[3001], i, j, n, res;
int main() {
  res = 0;
  scanf("%lld", &n);
  for (i = 2; i <= n; i++) {
    if (ar[i] == 2) res++;
    if (ar[i] != 0) continue;
    for (j = i; j <= n; j += i) ar[j]++;
  }
  printf("%lld\n", res);
  return 0;
}
