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.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int X = sc.nextInt();

		List<Integer> expList = new ArrayList<>();

		for (int i=1; i<=Math.sqrt(X); i++) {
			for (int j=2; j<10; j++) {
				if (Math.pow(i, j)<=X) {
					expList.add((int)Math.pow(i, j));
				}
			}
		}

		Collections.sort(expList);
		System.out.println(expList.get(expList.size()-1));
	}
}

