#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, counter = 0;
  cin >> n;
  int f[3001];
  bool x[3001];
  memset(x, false, sizeof(x));
  memset(f, 0, sizeof(f));
  for (int i = 2; i <= n; i++) {
    if (!x[i]) {
      for (int j = i; j <= n; j += i) {
        x[j] = true;
        f[j] += 1;
      }
    }
    if (f[i] == 2) {
      counter++;
    }
  }
  cout << counter << endl;
  return 0;
}
