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 = sc.nextInt();
        double max = 0;

        if(X==1){
            System.out.println(1);
        }
        else{
            for(int i=1; i<40; i++){
                for(int j=2; j<=10; i++){
                    if(Math.pow(i, j)<=X){
                        max = Math.max(max, Math.pow(i, j));
                    }
                    else{
                        break;
                    }
                }
            }
            System.out.println((int)max);
        }
    }
}