Coding Challenge - Body , C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var matrixXY = Int32.Parse(Console.ReadLine());
            int[,] matrix = new int[matrixXY,matrixXY];
            ReadMatrix(ref matrix,matrixXY);
            var waterBodySizes = FindSortedBodiesOfWater(ref matrix,matrixXY);
            foreach(var size in waterBodySizes)
            {
                Console.WriteLine(size);
            }
        }
        
        private static void ReadMatrix(ref int[,] matrix,int size)
        {
            for(int i = 0; i < size; ++i)
            {
                var items = Console.ReadLine().Split(' ');
                for(int j = 0; j < items.Length; ++j)
                {
                    var num = Int32.Parse(items[j]);
                    matrix[i,j] = num;
                }
            }
        }
        
        private static List<int> FindSortedBodiesOfWater(ref int[,] map, int size)
        {
            List<int> sizesOfWaterBodies = new List<int>();
            for(int i = 0; i < size; ++i)
            {
                for(int j = 0; j < size; ++j)
                {
                    int waterBodySize = GetBodyOfWaterSize(ref map, size, i, j);
                    if(waterBodySize > 0)
                    {
                        sizesOfWaterBodies.Add(waterBodySize);
                    }
                }
            }
            sizesOfWaterBodies.Sort();
            return sizesOfWaterBodies;
        }
                                              
      private static int GetBodyOfWaterSize(ref int[,] map, int sizeOfMap, int x, int y)
      {
          int sizeOfWater = 0;
          if(map[x,y] == 0)
          {
              map[x,y] = -1;
              ++sizeOfWater;
              // north
              if(y - 1 >= 0)
              {
                  sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap,x, y-1);
                  // northeast
                  if(x + 1 < sizeOfMap)
                  {
                      sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x + 1, y - 1);
                  }
                  // northwest
                  if(x - 1 >= 0)
                  {
                      sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x - 1, y - 1);
                  }
              }
              // east
              if(x + 1 < sizeOfMap)
              {
                  sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x+1,y);
              }
              // south
              if(y + 1 < sizeOfMap)
              {
                  sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x, y + 1);
                  // southeast
                  if(x + 1 < sizeOfMap)
                  {
                      sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x + 1, y + 1);
                  }
                  // southwest
                  if( x - 1 >= 0)
                  {
                      sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x - 1, y + 1);
                  }
              }
              // west
              if(x - 1 >= 0)
              {
                  sizeOfWater += GetBodyOfWaterSize(ref map, sizeOfMap, x - 1, y);
              }
          }
          return sizeOfWater;
      }
    }
}

Show compiler warnings [ - ] Show input
Compilation time: 0,14 sec, absolute running time: 0,08 sec, cpu time: 0,08 sec, average memory usage: 12 Mb, average nr of threads: 3