#include <bits/stdc++.h>
using namespace std;
int q[3001], t, n;
int main() {
  scanf("%d", &n);
  for (int i = 2; i <= n; i++) {
    if (q[i - 1] == 2) t++;
    if (q[i] > 0) continue;
    for (int j = i; j <= n; j += i) q[j]++;
  }
  if (q[n] == 2) t++;
  printf("%d\n", t);
}
