Problem:
Score : 200 points

Problem Statement

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.

Sample Input 1

10

Sample Output 1

9

There are four perfect powers that are at most 10: 1, 4, 8 and 9.
We should print the largest among them, 9.

Sample Input 2

1

Sample Output 2

1

Sample Input 3

999

Sample Output 3

961

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.util.Scanner;

public class Main {

	public static void main(String[] args){
		  Scanner sc = new Scanner(System.in);
		  int X = sc.nextInt();
		  sc.close();
		  
		  if(X == 1) {
			  System.out.println("1");
		      System.exit(0);
		  }
		  
		  int answer = 0;
		  
		  for(int base = 2; base <= Math.sqrt(X); base++) {
			  int i = 2;
			  while(Math.pow(base, i) <= X) {
				  answer = (int)Math.pow(base, i);
				  i++;
			  }
		  }
		 
		  System.out.println(answer);
	      System.exit(0);
	    }
}