#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main(int argc, const char *argv[]) {
  //
  ll a;
  cin >> a;

  ll ans = a;
  for (int i = 2; i * i <= a; ++i) {
    ll cur = i, j = 1;
    while (cur < a) {
      cur *= i;
      j++;
    }

    if (i * j < ans) {
      ans = i * j;
    } else {
      break;
    }
  }

  cout << ans << '\n';
}