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: Wrong Answer)

using System;

class Program
{
    static void Main(string[] args) {
        int x = int.Parse(Console.ReadLine());
        Console.WriteLine(solve(x));
    }
    static int solve(int x) {
        int ans = 1;
        for(int i = 2; i <= 1000; i ++) {
            int tmp = 1;
            for(int j = 2; j <= 1000; j ++) {
                tmp = tmp * i;
                if(tmp > x) break;
                ans = Math.Max(ans, tmp);
            }
        }
        return ans;
    }
}