Количество инверсий в массиве - C#

public class SortProblem
{
  public static void Main()
  {
    Sort();
  }
 
  public static void Sort()
  {
    var a = new [] 
    {
      11,86,232,28,8,145,588,1,307,179,77,792,693,678,481,888,574,695,624,866,467,434,907,259,130,37,25,373,214,268,108,672,371,866,863,279,22,233,336,830,374,439,144,234,360,617,244,5,566,847,476,493,56,618,202,576,179,972,898,970,119,214,786,38,71,404,420,827,814,201,865,341,358,794,492,27,290,672,899,512,792,20,807,367,792,615,616,753,663,287,99,49,334,366,711,160,652,105,162,955
    };

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
public class SortProblem
{
    static double inversionsCount;
 
    public static void Main()
    {
        var arr = new[]
    {
  11,86,232,28,8,145,588,1,307,179,77,792,693,678,481,888,574,695,624,866,467,434,907,259,130,37,25,373,214,268,108,672,371,866,863,279,22,233,336,830,374,439,144,234,360,617,244,5,566,847,476,493,56,618,202,576,179,972,898,970,119,214,786,38,71,404,420,827,814,201,865,341,358,794,492,27,290,672,899,512,792,20,807,367,792,615,616,753,663,287,99,49,334,366,711,160,652,105,162,955
};
        inversionsCount = 0;
        arr = Sort(arr);
        Console.Write($"{inversionsCount}");
        Console.ReadLine();
    }
 
    static int[] Sort(int[] buff)
    {
        if (buff.Length > 1) //Если длинна массива больше 1
 
        {
 
            int[] left = new int[buff.Length / 2]; // массив left равен длинна вставленного массива  разделить на 2
 
            int[] right = new int[buff.Length - left.Length]; // массив right  равен длинна вставленного массива минус массив left
 
            for (int i = 0; i < left.Length; i++)  // равно 0 , меньше длинны массива left, добавялем 1
            {
                left[i] = buff[i]; // результат left[i] = buff[i]
            }
            for (int i = 0; i < right.Length; i++) // массив right
            {
                right[i] = buff[left.Length + i];
            }
            /*Сортируем массивы*/
            if (left.Length > 1)
                left = Sort(left);
            if (right.Length > 1)
                right = Sort(right);
 
            buff = MergeSort(left, right);
        }
 
        return buff;
    }
    static int[] MergeSort(int[] left, int[] right)
    {
        int[] buff = new int[left.Length + right.Length];
 
        int i = 0;  //соединенный массив
        int l = 0;  //левый массив
        int r = 0;  //правый массив
 
        for (; i < buff.Length; i++)
        {
 
            if (r >= right.Length)
            {
                buff[i] = left[l];
                l++;
            }
 
            else if (l < left.Length && left[l] < right[r])
            {
                buff[i] = left[l];
                l++;
            }
 
            else
            {
                buff[i] = right[r];
                r++;
 
                if (l < left.Length)
                    inversionsCount += left.Length - l;
            }
        }
 
        return buff;
    }
 
}