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 AtCoder20200322
{
    class Program
    {
        static void Main(string[] args)
        {
            // TheNumberOfEvenPairs();
            MaxVolume();
        }
        
        public static void TheNumberOfEvenPairs()
        {
            String[] inputs = Console.ReadLine().Split(' ');
            int n = int.Parse(inputs[0]);
            int m = int.Parse(inputs[1]);

            int sum = nCm(n, 2) + nCm(m, 2);
            Console.WriteLine(sum);
        }

        public static int nCm(int n, int m)
        {
            if (m == 0) return 1;
            if (n == 0) return 0;
            return n * nCm(n - 1, m - 1) / m;
        }

        public static void MaxVolume()
        {
            double l = double.Parse(Console.ReadLine());
            double vol = Math.Pow(l, 3) / (double)27;
            Console.WriteLine(vol);
        }
    }
}