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 = Integer.parseInt(sc.next());
		sc.close();


		int ans = Integer.MIN_VALUE;
		if(X < 4) {
			System.out.println(1);
			return;
		}else {
			for(int i = 2; i <= Math.sqrt(X); i++) {
				int j = 1;
				int tmp = (int) Math.pow(i, j);
				while(tmp <= X) {
					j++;
					tmp = (int) Math.pow(i, j);
				}
				tmp = (int) Math.pow(i, j - 1);
				if(ans < tmp) {
					ans = tmp;
				}
			}
			System.out.println(ans);
		}

	}

}