#include <bits/stdc++.h>
using namespace std;
const int N = 3e3 + 1;
int factors[N];
void sieve() {
  memset(factors, 0, sizeof factors);
  for (int i = 2; i < N; ++i) {
    if (factors[i] == 0)
      for (int j = 2 * i; j < N; j += i) ++factors[j];
  }
}
int main(int argc, const char *argv[]) {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  sieve();
  int n;
  cin >> n;
  int ans = 0;
  for (int i = 1; i <= n; ++i)
    if (factors[i] == 2) ++ans;
  cout << ans << '\n';
  return 0;
}
