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 sc = new Scanner(System.in);
		int X = sc.nextInt();
		long max = 1;
		for (int i = 1; i <= Math.sqrt(X); i++) {
			for (int j = 2; j <= Math.sqrt(X); j++) {
				long let = (long)Math.pow(i, j);
				if (let <= X && let > max) {
					max = let;
				}
			}
		}
		System.out.println(max);
		}

}
