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>
#include<algorithm>

int main() {
  int X;
  std::cin >> X;

  int maxE=1;
  for (int i=2;i<=X;i++) {
    for (int j=i*i;j<=X;j*=i) {
      maxE = std::max(maxE,j);
    }
  }

  std::cout << maxE << '\n';
  return 0;
}
