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 N = sc.nextInt();

        int res=1;
        
        for(int i=2; i<100; i++){
            for(int j=2; j<11; j++){
                if(Math.pow(i,j)<=N){
                    res = (int)Math.max(res,Math.pow(i,j));
                }else{
                    break;
                }
            }

        }

        System.out.println(res);
        
        
        
        
        
        }
    }