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: Accepted)

import java.util.*;
public class Main {
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int x = sc.nextInt();
    int count = 0;
    
    //x以下の間繰り返す
    for(int i = 0; i <= x; ++i){
      //1からべき乗か調べる
      for(int j = 2; j <= x; ++j){
        if((Math.pow(i,j)<= x) && (count<Math.pow(i,j))){
          count = (int)Math.pow(i,j);
        }
      }
    }
    if(count==0){
      count = 1;
    }
    System.out.println(count);
    
  }
}