#include <iostream>
using namespace std;

int main() {
    long long A; cin >> A;
    long long min_ = 1000000000;
    for (long long i = 2; i < 100; i++){
        long long B = 1;
        long long count = 0;
        while (A / i > B){
            B *= i;
            count++;
        }
        count++;
        min_ = min(min_, count * i);
    }
    cout << min_ << endl;
}