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 max = 1;

    for(int b=1;b<32;b++){
      for(int p=2;p<10;p++){
        double exp = Math.pow(b,p);
        if(exp>X){
          break;
        }
        if(max < exp){
          max = (int)exp;
        }
      }
    }
    System.out.println(max);
  }
}
