Problem:
Score : 300 points

Problem Statement

Given is a positive integer L.
Find the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.

Constraints

1 ≤ L ≤ 1000

L is an integer.

Input

Input is given from Standard Input in the following format:

L

Output

Print the maximum possible volume of a rectangular cuboid whose sum of the dimensions (not necessarily integers) is L.
Your output is considered correct if its absolute or relative error from our answer is at most 10^{-6}.

Sample Input 1

3

Sample Output 1

1.000000000000

For example, a rectangular cuboid whose dimensions are 0.8, 1, and 1.2 has a volume of 0.96.

On the other hand, if the dimensions are 1, 1, and 1, the volume of the rectangular cuboid is 1, which is greater.

Sample Input 2

999

Sample Output 2

36926037.000000000000

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

using System;

namespace ABC159
{
    internal class Program
    {
        public static void Main(string[] args)
        {
            var s = Console.ReadLine();
            var l = int.Parse(s);

            var p = new ProblemC();
            Console.WriteLine(p.GetAnswer(l));
        }
    }

    public class ProblemC
    {
        public double GetAnswer(double l)
        {
            var x = l / 3;
            return x * x * x;
        }
    }
}