#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

ll a;
bool check(ll x) {
  for (ll n = 1; n <= x; n++) {
    if (x%n==0) {
      ll m = x/n;
      ll tmp = 1;
      rep(i,m) tmp *= n;
      if (tmp >= a) return true;
    }
  }
  return false;
}

int main() {
  cin >> a;
  for (ll i = 1; i < 181; i++) {
    if (check(i)) {
      cout << i << endl;
      return 0;
    }
  }

}