#include <iostream>
#include <cmath>

using namespace std;

int main(){

    long long a,mmi,mma;
    cin>>a;
    mmi=max(floor(log(a)),1.0);
    mma=mmi+1;

    long long ans=ceil(pow(a,1.0/mmi))*mmi;
    ans=min(ans,(long long)ceil(pow(a,1.0/mma))*mma);
    cout<<ans<<endl;

    return 0;
}