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

using LL=__int128_t;
int main() {
    ll n;
    cin>>n;
    LL N=n;
    vector<LL> P={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59,61};
    LL u=1;
    for(int j=0;j<100;j++){
        u*=P[j];
        if(u>N){
            cout<<j<<endl;
            return 0;
        }
    }
}