#include <bits/stdc++.h>

using ll = long long;
using namespace std;
const int INFint = 1e9+1;
const ll INFll = (ll)1e18+1;
ll MOD=1e9+7;

int main(){
  ll A;
  cin>>A;
  int ans(1e9);
  for(int i(2);i<100;i++){
    ll tmp(1);
    int cnt(0);
    while(tmp < A){
      tmp *= i;
      cnt++;
    }
    ans = min(ans,i*cnt);
  }
  cout << ans << endl;
  return 0;
}