#include <bits/stdc++.h>
using namespace std;
int a[10];
bool ok(int k) {
  int n = 0, j = 2;
  while (k != 1) {
    if (k % j == 0) {
      while (k % j == 0) k /= j;
      a[++n] = j;
    }
    j++;
  }
  if (n == 2) return 1;
  return 0;
}
int main() {
  int n, cnt = 0;
  cin >> n;
  for (int i = 1; i <= n; i++) {
    if (ok(i)) cnt++;
  }
  cout << cnt;
  return 0;
}
