#include <bits/stdc++.h>
using namespace std;
int main(){
    #define int long long
    long long a;
    cin >> a;
    long long ans = a;
    for(long long m = 2;m <= 100;++m){
        int hoge = ceil(pow(a,1.0L / (long double)m));
        ans = min(ans,hoge * m);
    }
    cout << ans << endl;
}