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 main()
{
  int x, i;
  cin >> x;
  int ans = 1;
  for (i = 2; i*i <= x; i++) {
    int sum = 1;
    while (i*sum <= x)
      sum *= i;
    if (sum > ans)
      ans = sum;
  }
  cout << ans << endl;
}
