如何在我的代码中添加组合的总数？C#

using System;

class Program
{
    static void Main()
    {
        int n = 5; // 总元素数
        int k = 2; // 选择的元素数

        long combinationCount = CalculateCombination(n, k);
        Console.WriteLine($"C({n}, {k}) = {combinationCount}");
    }

    static long CalculateCombination(int n, int k)
    {
        if (k > n)
            return 0;

        if (k == 0 || k == n)
            return 1;

        long result = 1;
        for (int i = 1; i <= k; ++i)
        {
            result *= n - (k - i);
            result /= i;
        }

        return result;
    }
}