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();
    	if (X < 4) {
    		System.out.println(1);
    	} else {
        	int ans = 0;
        	for (int i = 2; i <= X; i++) {
        		int d = 0;
        		for (int j = 2; d <= X; j++) {
        			if (ans < d) {
        				ans = d;
        			}
        			d = (int) Math.pow(i, j);
        		}
        	}
        	System.out.println(ans);
    	}
    }
}