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;

class Main{
	int X;

  public static void main(String[] ar){
    new Main();
  }
  public Main(){
  	Scanner sc=new Scanner(System.in);
  	String line=sc.nextLine();
  	X=Integer.parseInt(line);  	
  	//System.out.println(X);
  	
    int E=0;
    for(double r=2;r<=10;r++){
      int a=(int)Math.pow((int)Math.pow(X+0.1, 1.0/r), r);
      if(E<a) E=a;
    } 
    System.out.println(E);
  }
}