#include <bits/stdc++.h>

#define rep(X,N) for(ll X = 0LL; X < (N); X++)
#define ALL(V) (V).begin(),(V).end()
#define endl "\n"

using namespace std;
typedef long long ll;

const double PI = 3.1415926535897932384626;
const ll MODN = 1000000007;
const ll MODN2 = 998244353;
const double EPS = 1e-10;

int main(){

    ll a;
    cin >> a;

    int ans = 129;

    for(int i = 2; i < 6; i++){
        ll tmp = 1;
        int count = 0;

        while(tmp < a){
            tmp *= i;
            count++;
        }

        ans = min(ans, count * i);
    }

    cout << ans << endl;


    return 0;
}