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.io.*;
import java.util.*;
import java.math.BigInteger;
public class Main {

static long[] list=new long[87];

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

   String nyuA=sc.nextLine();
int X=Integer.parseInt(nyuA);

int ans=1;

for(int b=2;b<=X;b++){
int power=b*b;
for(int p=2;;p++){
if(power>X)break;
ans=Math.max(ans,power);
power*=b;
}
}
System.out.println(ans);
}

}

