StringToIntAndTakeLastDigitOfASCII

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

namespace Problem18EncryptedMatrix
{
    class Program
    {
        static void Main(string[] args)
        {
            string letters = Console.ReadLine();
            string direction = Console.ReadLine();

            int[] numbers = new int[letters.Length];
            int[] numbersCopy = new int[numbers.Length];
            for (int i = 0; i < numbers.Length; i++)
            {
                numbers[i] = Convert.ToInt32(letters[i]) % 10;
                numbersCopy[i] = Convert.ToInt32(letters[i]) % 10;
            }

            for (int i = 0; i < numbers.Length; i++)
            {
                if (numbers[i] % 2 == 0)
                {
                    numbersCopy[i] *= numbers[i];
                }
                else
                {
                    if (i > 0 && i <= numbers.Length - 2)
                    {
                        numbersCopy[i] += numbers[i + 1] + numbers[i - 1];
                    }
                    else if (i == numbers.Length - 1)
                    {
                        if (numbers.Length == 1)
                        {
                            continue;
                        }
                        else
                        {
                            numbersCopy[i] += numbers[i - 1];
                        }
                    }
                    else
                    {
                        numbersCopy[i] += numbers[i + 1];
                    }
                }
            }

            string getNumbers = string.Empty;
            for (int i = 0; i < numbersCopy.Length; i++)
            {
                getNumbers += numbersCopy[i];
            }

            int length = getNumbers.Length;
            int[,] matrix = new int[length, length];

            if (direction == "/")
            {
                for (int i = 0; i < length; i++)
                {
                    matrix[length - i - 1, i] = int.Parse(getNumbers[i].ToString());
                }
            }
            else
            {
                for (int i = 0; i < length; i++)
                {
                    matrix[i, i] = int.Parse(getNumbers[i].ToString());
                }
            }

            for (int i = 0; i < length; i++)
            {
                for (int j = 0; j < length; j++)
                {
                    Console.Write(matrix[i, j] + " ");
                }
                Console.WriteLine();
            }
        }
    }
}