Hourglass Hackerrank

using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Collections;
using System.ComponentModel;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Runtime.Serialization;
using System.Text.RegularExpressions;
using System.Text;
using System;



class Solution
{
    public static void Main(string[] args)
    {

        List<List<int>> arr = new List<List<int>>();

        for (int i = 0; i < 6; i++)
        {
            arr.Add(Console.ReadLine().TrimEnd().Split(' ').ToList().Select(arrTemp => Convert.ToInt32(arrTemp)).ToList());
        }

        int bestSum = int.MinValue;
            int currentSum = 0;
            for(int row = 0; row < 4; row++)
            {
                for(int col = 0; col < 4; col++)
                {
                    currentSum = arr[row][col] + arr[row][col+1] + arr[row][col+2] + arr[row+1][col+1]+ arr[row+2][col] + arr[row+2][col+1] + arr[row+2][col+2];
                    if(currentSum > bestSum)
                    {
                        bestSum = currentSum;
                    }
                    currentSum = 0;
                }
            }
            Console.WriteLine(bestSum);
    }
}