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 <cstdio>
#include <algorithm>

int main() {
  int X;
  scanf("%d", &X);

  int res = 1;
  for (int i = 2; i <= 32; ++i)
    for (int j = i*i; j <= X; j *= i)
      res = std::max(res, j);

  printf("%d\n", res);
}