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();
		int answer = 1;
		if (X <= 3) {
			System.out.println("1");
		} else {
			for (int i = 2 ; i <= 31; i++) {
				int candidate = i;
				while ( candidate * i <= X) {
					candidate *= i ;
					answer = Math.max(answer, candidate);
			}

		}
			System.out.println(answer);
		}

}
}