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.lang.reflect.Array;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Scanner;


class Main {
    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	int x = sc.nextInt();
    	int xx = x / 2;
    	int ans = 0;

    	for(int i = 1; i <= x; i++){
    		for(int j = 2; j <= x + 1; j++){
    			if(Math.pow(i, j) > ans && Math.pow(i, j) <= x){
    				ans = (int)Math.pow(i, j);
    			}
    		}
    	}

    	System.out.println(ans);
    }
}