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();
	int a = 0;
	boolean tf = true;

	for(int i=x;i>0;i--){

	    if(tf == false) break;
	    
	    for(int j=1;j<=i;j++){
		
		a = j;
		
		for(int k=1;k<=i;k++){

		    a = a * a;

		    if(i == a){
			System.out.println(a);
			tf = false;
		    }
		}
	    }
	}
    }
}