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;
using System.Text;
using System.Threading.Tasks;

namespace abc159
{
    class Program
    {
        static void Main(string[] args)
        {
            //a();
            c();
        }

        public static void a()
        {
            int[] nm = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int n = nm[0], m = nm[1];
            int ans = 0;
            
            Console.WriteLine(ans);
        }

        public static void c()
        {
            double l = double.Parse(Console.ReadLine());
            double x = l / 3.0;
            double ans = x * x * x;
            Console.WriteLine(ans);
        }
        
    }
}