#include <bits/stdc++.h>
using namespace std;
const int M = 3005;
const int INF = 1e9;
const int MOD = 1e9 + 7;
int n;
int p[M];
void criba() {
  for (int i = 2; i < n; i++)
    if (!p[i])
      for (int j = 1; i * j < n; j++) p[i * j]++;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  n++;
  criba();
  int cont = 0;
  for (int i = 2; i < n + 1; i++)
    if (p[i] == 2) cont++;
  cout << cont << "\n";
  return 0;
}
