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 Java (OpenJDK 11.0.6) (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 i=0;
    //べき乗数を探す
    for(i=X;i>0;i++){
      if(judge(i)){
        break;
      }
    }
    System.out.println(i);
  }
    //べき乗数かどうか
    private static boolean judge(int n){
      boolean re = false;
      for(int i=1;i<n;i++){
        for(int j=1;j<n;j++){
          int m = (int)Math.pow(i,j);
          if(m==n){
            re = true;
            break;
          }
        }
      }
        return re;
      }
}