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
import java.util.*;
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    int X = sc.nextInt();
    int ans = 0;
    for (int i = 2; i <= 9; i++) {
      for (int j = 0; j <= 31; j++) {
        if (X >= (int) Math.pow(j, i)) {
          ans = Math.max(ans, (int) Math.pow(j, i));
        }
      }  
    }
    System.out.println(ans);
  }
}