#include <bits/stdc++.h>
using namespace std;
bool isprim(int n) {
  if (n == 2) return 1;
  if (n % 2 == 0 || n < 2) return 0;
  for (int i = 3; i * i <= n; i += 2)
    if (n % i == 0) return 0;
  return 1;
}
int main() {
  vector<int> myvec;
  int n, counter = 0;
  cin >> n;
  for (int i = 2; i <= n; i++)
    if (isprim(i)) myvec.push_back(i);
  int len = myvec.size();
  for (int i = 3; i <= n; i++) {
    int cnt = 0;
    for (int j = 0; j < len; j++) {
      if (i >= myvec[j])
        if (i % myvec[j] == 0 && myvec[j] * myvec[j] != i) cnt++;
    }
    if (cnt == 2) counter++;
  }
  cout << counter << endl;
  return 0;
}
