#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

const ll pfs[16] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53};

void solve() {
  ll n;
  cin >> n;
  double now = 1.0;
  rep(i, 16) {
    now *= pfs[i];
    if (n < now - 0.1) {
      cout << i << '\n';
      return;
    }
  }
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}