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.*;
 
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = Integer.parseInt(sc.next());
        List l = new ArrayList<>();
        int max = 0;
        for(int i = 2; i <= Math.sqrt(x); i++) {
            int j = 2;
            while(true) {
                if(Math.pow(i, j) > x) {
                    break;
                }
                if(l.contains(Math.pow(i, j))) {
                    break;
                }else {
                    if(max < Math.pow(i, j)) {
                        max = (int)Math.pow(i, j);
                    }
                }
                j++;
            }
        }
        System.out.println(max);
    }
}