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.io.IOException;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		Scanner sc = new Scanner(System.in);

		int x = sc.nextInt();

		int result = 1;
		for(int i = 2; i <= x - 1; i++){
			int p = 2;

			while(Math.pow(i, p) <= x){
				result = (int)Math.max(result, Math.pow(i, p));
				p++;
			}
		}

		System.out.println(result);
	}
}
