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

int main() {
  long A;
  cin >> A;
  if (A == 1) return cout << 1 << "\n", 0;
  int ans = 1e9;
  for (int i = 2; i < 1e6; i++) {
    long double tmp = i;
    int cnt = 1;
    while (tmp < A) tmp *= i, cnt++;
    ans = min(ans, i * cnt);
  }
  cout << ans << "\n";
}