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: Accepted)

import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
    
		// 整数の入力
		int x = sc.nextInt();
		int ans = 1;
        int b = 1;
      
        if (x == 1) {
          // 出力
		  System.out.println(ans);
          return;
        }
      
        Parent: while(true) {
          b++;
          if (Math.pow(b, 2) > x) {
            break Parent;
          }
          int p = 2;
          Child: while(true) {
            int value = (int)Math.pow(b, p);
            if (value > x) {
              break Child;
            } else if (value > ans) {
              ans = value;
            }
            p++;
          }
        }
    
		// 出力
		System.out.println(ans);
	}
}