AddsTwoPositiveNumbers

using System;
//Write a method that adds two positive integer numbers represented as arrays of digits (each array element arr[i] contains a digit; the last digit is kept in arr[0]). Each of the numbers that will be added could have up to 10 000 digits.

class AddsTwoPositiveNumbers
{
    // Convert string to array
    static string[] InputElemOfStrToArray(string numStr)
    {
        string[] array = new string[numStr.Length];
        for (int i = 0; i < numStr.Length; i++)
        {
            array[i] = numStr[i].ToString();
        }
        return array;
    }
    // Collection of the two arrays by index
    private static string[] SumArrays(string[] firstArray, string[] secArray)
    {
        int currentSum = 0;
        string sumStr = " ";
        bool check = true;
        int remainder = 0;
        int maxLength = (firstArray.Length - 1);
        int minLength = (secArray.Length - 1);
        // Summation of the array in sumStr
        for (int i = maxLength, j = minLength; i >= 0; i--)
        {
            currentSum = (int.Parse(secArray[j]) + int.Parse(firstArray[i]));
            if (currentSum < 10)
            {
                sumStr += Convert.ToString(currentSum) + " ";
            }
            else
            {
                remainder = currentSum % 10;
                sumStr += Convert.ToString(remainder) + " ";

                if (i > 0)
                {   // If we have remainder increase nex elem with one
                    int increase = (int.Parse(firstArray[i - 1]) + 1);
                    firstArray[i - 1] = increase.ToString();
                }
                else
                {
                    sumStr += 1;
                }
            }
            // Modeling 'j'
            if ((j >= 0) && check)
            {
                if (j == 0)
                {
                    secArray[j] = "0";
                    check = false;
                    j++; // Stop out of range exept.
                }
                j--;
            }
        }
        string[] unnecessaryElements = new string[] {" "}; // Remove empty spaces in array
        string[] SplitSumStrArr = sumStr.Split( unnecessaryElements,StringSplitOptions.RemoveEmptyEntries );
        Array.Reverse(SplitSumStrArr); // Reverse array SplitSumArr
        return SplitSumStrArr;
    }

    static void Main(string[] args)
    {
        string[] firstArray;
        string[] secArray;
        Console.WriteLine("Enter the first integer");
        string firstNum = Console.ReadLine();

        Console.WriteLine("Enter the second integer");
        string secNum = Console.ReadLine();
        // Most larger number adds to firstArray
        if (firstNum.Length > secNum.Length)
        {
            firstArray = InputElemOfStrToArray(firstNum);
            secArray = InputElemOfStrToArray(secNum);
        }
        else
        {
            firstArray = InputElemOfStrToArray(secNum);
            secArray = InputElemOfStrToArray(firstNum);
        }

        string[] arraySum = SumArrays(firstArray, secArray);
        Console.WriteLine(string.Join("", arraySum));
    }
}