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;
using System.Collections.Generic;
using System.Linq;

namespace C
{
    internal static class Program
    {
        private static void Main(string[] args)
        {
            var l = Cint();
            
            Cout(Math.Pow((double) l / 3, 3));
        }

        #region Input and Output

        private static readonly List<string> Buffer = new List<string>();

        private static string Cin()
        {
            ReadBuffer();

            var str = Buffer.First();
            Buffer.RemoveAt(0);

            return str;
        }

        private static IEnumerable<string> CinA() => Console.ReadLine()?.Split();
        private static int Cint() => int.Parse(Cin());
        private static int[] CintA() => CinA().Select(int.Parse).ToArray();
        private static void Cout(object obj) => Console.WriteLine(obj);

        private static void ReadBuffer()
        {
            if (Buffer.Any()) return;

            var line = Console.ReadLine();
            if (line != null && line.Contains(' '))
            {
                Buffer.AddRange(line.Split());
            }
            else
            {
                Buffer.Add(line);
            }
        }

        #endregion

        #region Loops

        private static void Loop(int count, Action<int> action) => Loop(0, count, action);

        private static void Loop(int init, int count, Action<int> action, int step = 1)
        {
            for (var i = init; i < count + init; i += step)
            {
                action(i);
            }
        }

        #endregion
    }
}