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.*;
import static java.lang.Math.*;
import java.math.BigInteger;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		// 入力
		int x = sc.nextInt();
		
		// 計算
		int result = 1;
		for(int i = 1; i <= x; i++){
		    for(int j = 2; j <= x; j++){
		        if((int)pow(i, j) <= x) result = max(result, (int)pow(i, j));
		    }
		}
		
		// 出力
		System.out.println(result);
	}
}
