using System.Collections.Generic;
public static void Main()
public static void AddStrings(string num1, string num2){
var maxLen = num2.Length > num1.Length ? num2.Length : num1.Length;
var result = new List<char>();
for(int i=0 ; i < maxLen ; i++){
int fir = (num1.Length - 1 - i) < 0 ? 0 : Int32.Parse(num1[num1.Length - 1 -i].ToString());
int sec = (num2.Length - 1 - i) < 0 ? 0 : Int32.Parse(num2[num2.Length - 1 -i].ToString());
var sum = fir + sec + digit;
result.Add((char)(_n + '0'));
if(i == maxLen-1 && digit !=0){
result.Add((char)(digit+ '0'));
Console.WriteLine(new string(result.ToArray()));