Combinations

using System;

namespace Combinations
{
    class Program
    {
        static void Main(string[] args)
        {
            int num = int.Parse(Console.ReadLine());
            int validCombinationsCount = 0;

            for (int x1 = 0; x1 <= num; x1++)
            {
                for (int x2 = 0; x2 <= num; x2++)
                {
                    for (int x3 = 0; x3 <= num; x3++)
                    {
                        if (x1 + x2 + x3 == num)
                        {
                            validCombinationsCount++;

                        }
                    }

                }
            }
            Console.WriteLine(validCombinationsCount);
        }
    }
}