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[]) {
	int b = 1;
	int p = 2;
	double max = 0;
	double result;
	Scanner scanner = new Scanner(System.in);
	int x = scanner.nextInt();
	while (b < 1000) {
	    while (p < 1000) {
		result = Math.pow(b, p);
		if (result > x ) break;
		if (result >= max) max = result;
		p++;
	    }
	    p = 2;
	    b++;
	}
	System.out.println((int)max);
    }
    
}
