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.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int X = sc.nextInt();


        // べき乗数のリストをつくる
		Set<Integer> set = new HashSet<>();

		set.add(1);

		for (int i = 2; i < 32; i++) {
			for (int j = 2; j < 10; j++) {
				set.add((int)Math.pow(i, j));
			}
		}

		for(int i = 0; i < X; i++) {
			if (set.contains(X-i)) {
				System.out.println(X-i);
				return;
			}
		}
    }
}
