#include <bits/stdc++.h>
using namespace std;

using ll = long long;

int main() {
    ll n;
    cin >> n;
    vector<ll> p = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47};
    ll m = 1;
    for(ll i = 0; i < 15; i++){
        m *= p[i];
        if(m > n){
            cout << i << endl;
            return 0;
        }
    }
    cout << 15 << endl;
}