3.Maximal Sum/ C# Advanced

using System;
using System.Linq;
using System.Security.Cryptography.X509Certificates;

namespace _3._Maximal_Sum
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] rectangularMatrixSizes = Console.ReadLine()
                .Split(" ", StringSplitOptions.RemoveEmptyEntries)
                .Select(int.Parse)
                .ToArray();

            int rows = rectangularMatrixSizes[0];
            int cols = rectangularMatrixSizes[1];

            int[,] rectangularMatrix = ReadMatrix(rows, cols);

            int maxSum = Int32.MinValue;
            int bestRow = 0;
            int bestCol = 0;

            for (int row = 0; row < rows - 2; row++)
            {
                for (int col = 0; col < cols - 2; col++)
                {
                    int firstRowSum = rectangularMatrix[row, col] + rectangularMatrix[row, col + 1] +
                                      rectangularMatrix[row, col + 2];
                    int secondRowSum = rectangularMatrix[row + 1, col] +
                                       rectangularMatrix[row + 1, col + 1] + rectangularMatrix[row + 1, col + 2];
                    int thirdRowSum = rectangularMatrix[row + 2, col] + rectangularMatrix[row + 2, col + 1] +
                                      rectangularMatrix[row + 2, col + 2];
                    int currentSum = firstRowSum + secondRowSum + thirdRowSum;

                    if (currentSum > maxSum)
                    {
                        maxSum = currentSum;
                        bestRow = row;
                        bestCol = col;
                    }
                }
            }

            Console.WriteLine($"Sum = {maxSum}");
            for (int row = bestRow; row <= bestRow + 2; row++)
            {
                for (int col = bestCol; col <=  bestCol + 2; col++)
                {
                    Console.Write(rectangularMatrix[row, col] + " ");
                }
                Console.WriteLine();
            }
        }

        static int[,] ReadMatrix(int rows, int cols)
            {
                int[,] rectangularMatrix = new int[rows, cols];
                for (int rowIndex = 0; rowIndex < rows; rowIndex++)
                {
                    int[] numbersToInput = Console.ReadLine()
                        .Split(" ", StringSplitOptions.RemoveEmptyEntries)
                        .Select(int.Parse)
                        .ToArray();
                    for (int colIndex = 0; colIndex < cols; colIndex++)
                    {
                        rectangularMatrix[rowIndex, colIndex] = numbersToInput[colIndex];
                    }
                }

                return rectangularMatrix;
            }
        }
    }