You are given a positive integer X. Find the largest perfect power that is at most X. Here, a perfect power is an integer that can be represented as b^p, where b is an integer not less than 1 and p is an integer not less than 2.

Constraints

* 1 ≤ X ≤ 1000
* X is an integer.

Input

Input is given from Standard Input in the following format:


X


Output

Print the largest perfect power that is at most X.

Examples

Input

10


Output

9


Input

1


Output

1


Input

999


Output

961
#include <iostream>
using namespace std;

int a;
int main() {
  cin >> a;
  
  int mx = 1;
  for (int i = 2; i * i <= a; ++i) {
    int base = i * i;
    while (base <= a) {
      mx = max(mx, base);
      base *= i;
    }
  }
  cout << mx << endl;
}
