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.Linq;
using System.Collections.Generic;
using static System.Console;
using static System.Math;
 
public class Hello{
    public static void Main(){
/*        string[] input = ReadLine().Split(' ');
        long a = long.Parse(input[0]);
        long b = long.Parse(input[1]);
        long c = long.Parse(input[2]);
        long d = long.Parse(input[3]);*/
//        string temp = ReadLine();
        int a = int.Parse(ReadLine());
//        int b = int.Parse(ReadLine());
//        int c = int.Parse(ReadLine());
//        int d = int.Parse(ReadLine());
//        string a = ReadLine();
//        string b = ReadLine();
//        string c = ReadLine();
//        string[] input = ReadLine().Split(' ');
//        string ko = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        int max = 0;
        if(a >= 1 && a <= 3){ WriteLine(1); }
        else{
        for(int i=2;i<33;i++){
            if(i < a){
                int k = i;
                while(k <= a){
                    k *= i;
                    if(k<=a){
                        max = Max(k,max);
                    }
                }
            }
        }
        WriteLine(max);
        }
    }
}