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.*;

class Main
{
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        int ans = 1;

        if(x >= 4){
            for(int i=2; i < 32; i++)
            {
                int j=1;
                double num = 1;
                while(num <= x){
                    j++;
                    num = Math.pow(i, j);
                }
                num = num/i;
                if(num > ans){
                    ans = (int)(num);
                }
            }
        }
        System.out.println(ans);
    }
}