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.Scanner;

public class Main {
	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		
		int pow = 0;
		int ans = 1;
		for (int i = 1; i < n; i++) {
			for (int j = 2; j < n; j++) {
				pow = (int) Math.pow(i, j);
				if (pow <= n) {
					ans = Math.max(ans, pow);
				}
			}
		}
		System.out.println(ans);
	}
}