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

public class Solve
{
    static void Main(string[] args)
    {
        new ABC_C();
    }
}
public class ABC_A
{
    public ABC_A()
    {
        var inn = Ex.ReadIntArray();
        int n = inn[0];
        int m = inn[1];
        Console.WriteLine(n * (n - 1) / 2 + m * (m - 1) / 2);
    }
}
public class ABC_B
{
    public ABC_B()
    {
        string s = Ex.Read;
        int n = s.Length;
        Console.WriteLine((c1(s, 1, n) && c1(s, 1, (n - 1) / 2) && c1(s, (n + 3) / 2, n)) ? "Yes" : "No");
    }

    bool c1(string s, int ss, int ee)
    {
        int i = 0;
        while ((ss + i - 1) <= (ee / 2))
        {
            if (s[ss + i - 1] != s[ee - i - 1]) return false;
            i++;
        }

        return true;
    }
}
public class ABC_C
{
    public ABC_C()
    {
        string s = Ex.Read;
        ulong l = ulong.Parse(s);
        var d = (l / 3.0);
        Console.WriteLine(d*d*d);
    }
}
public class ABC_D
{
    public ABC_D()
    {

    }
}
public class ABC_E
{
    public ABC_E()
    {

    }
}
public class ABC_F
{
    public ABC_F()
    {

    }
}
public static class Ex
{
    public static string Read { get { return Console.ReadLine().Trim(); } }
    public static int ReadInt { get { return int.Parse(Read); } }
    public static long ReadLong { get { return long.Parse(Read); } }
    public static double ReadDouble { get { return double.Parse(Read); } }
    public static string[] ReadArray() { return Read.Split(' '); }
    public static int[] ReadIntArray() { return Read.Split(' ').Select(s => int.Parse(s)).ToArray(); }
    public static long[] ReadLongArray() { return Read.Split(' ').Select(s => long.Parse(s)).ToArray(); }
    public static string[] ReadArray(long N) { var ret = new string[N]; for (long i = 0; i < N; ++i) ret[i] = Read; return ret; }
    public static int[] ReadIntArray(long N) { var ret = new int[N]; for (long i = 0; i < N; ++i) ret[i] = ReadInt; return ret; }
    public static long[] ReadLongArray(long N) { var ret = new long[N]; for (long i = 0; i < N; ++i) ret[i] = ReadLong; return ret; }
}