[C#] Max Platform 3 x 3

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _05.Max_Platform_3_x_3
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] pos = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            int rows = pos[0];
            int cols = pos[1];
            int[][] matrix = new int[rows][];
            for (int i = 0; i < rows; i++)
            {
                matrix[i] = Console.ReadLine().Split(' ').Select(int.Parse).ToArray();
            }
            long maxSum = int.MinValue;
            int startRow = 0;
            int startCol = 0;

            for (int i = 0; i < rows - 2; i++)
            {
                for (int j = 0; j < cols - 2; j++)
                {

                    long sum = TmpSum(matrix, i, j);
                    if (maxSum < sum)
                    {
                        maxSum = sum;
                        startRow = i;
                        startCol = j;
                    }
                }
            }
            Console.WriteLine(maxSum);
            for (int i = startRow; i < startRow + 3; i++)
            {
                for (int j = startCol; j < startCol + 3; j++)
                {
                    Console.Write(matrix[i][j] + " ");
                }
                Console.WriteLine();
            }
        }
        static long TmpSum(int[][] matrix,int row,int col)
        {
            long sum = 0;
            for (int tmpRow = row; tmpRow < row+3; tmpRow++)
            {
                for (int tmpCol = col; tmpCol < col+3; tmpCol++)
                {
                    sum += matrix[tmpRow][tmpCol];
                }
            }
            return sum;
        }

    }
}