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 = 0;

		if(X!=1){
			for(int b=2; b<Math.sqrt(X); b++){
				int p=2;
				int pow = (int) Math.pow(b,p);
				while(pow<=X){
					if(max<pow){
						max=pow;
					}
					p++;
					pow = (int) Math.pow(b,p);
				}
			}
		}else{
			System.out.println("1");
			return;
		}
		System.out.println(max);
    }
}