/* -*- coding: utf-8 -*-
 *
 * 1176.cc:  No.1176 少ない質問 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

/* typedef */

typedef long long ll;

/* global variables */

/* subroutines */

/* main */

int main() {
  ll a;
  scanf("%lld", &a);

  int k = 0;
  for (ll bi = 1; bi < a; bi <<= 1, k++);
  //printf("k=%d\n", k);

  ll maxnm = a;
  for (int m = 2; m <= k; m++) {
    ll nm = (ll)ceil(pow(a, 1.0 / m)) * m;
    if (maxnm > nm) maxnm = nm;
  }

  printf("%lld\n", maxnm);
  return 0;
}