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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

    using System;
    using System.Text;
    using System.Collections.Generic;
    using static System.Math;
    using System.Linq;
    using static System.Array;
    
    namespace ConsoleApp2
    {
    class Program
    {
        static long H;
        static long W;
        static String[] map;
        static void Main(string[] args)
        {

            //var NK = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
            var X = long.Parse(Console.ReadLine());

            var ans = 1L;
            for (int i = 2; i <= 100; i++)
            {
                for (int j = 2;; j++)
                {
                    var tmp = (long)Pow(i, j);
                    if (X >= tmp)
                    {
                        ans = Max(ans, tmp);
                    }
                    else
                    {
                        break;
                    }
                        
                }
            }

            Console.WriteLine(ans);
            
        }
    }

}