#include <iostream>
using namespace std;
int main(){
    unsigned long long n;cin>>n;
    unsigned long long ans = n;
    for(unsigned long long i = 2; 128 >= i; i++){
        unsigned long long j = 1;
        unsigned long long t = 0;
        for(;n>j;j*=i)t++;
        ans = min(ans,i*t);
        
    }
    cout << ans << endl;
}