#include <bits/stdc++.h>
using namespace std;
#include <boost/multiprecision/cpp_int.hpp>
namespace mp=boost::multiprecision;

mp::cpp_int binary_search(mp::cpp_int m,mp::cpp_int M,function<bool(mp::cpp_int)> a){//m以上M未満で条件を満たす最小の整数を返す。いずれも満たさない場合Mを返す。
    --m;
    while(M-m>1){
        mp::cpp_int mid=(M+m)/2;
        if(a(mid)){
            M=mid;
        }else{
            m=mid;
        }
    }
    return M;
}

int main(){
    mp::cpp_int A;
    cin>>A;
    mp::cpp_int ans=A;
    for(int M=2;(1<<(M-1))<A;++M){
        mp::cpp_int N=binary_search(0,A,[M,A](mp::cpp_int a){
            return pow(a,M)>=A;
        });
        ans=min(ans,N*M);
    }
    cout<<ans<<endl;
}