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.*;
import java.lang.Math;

public class Main {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);

        int x = sc.nextInt();
        int max = 1;
        int i = 2;

        while (i * i <= x) {
            int m = i * i;
            while (m <= x) {
                if (m > max) {
                    max = m;
                }
                m *= i;
            }
            i++;
        }

        System.out.println(max);
    }
}