using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        String num1="9";

        String num2 = "99";

        AddStrings(num1,num2);

    }

    public static void AddStrings(string num1, string num2){

        var maxLen = num2.Length > num1.Length ? num2.Length : num1.Length;

        var result = new List<char>();

        int digit = 0;

        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;

            var _n = sum % 10;

            digit = sum/10;

            result.Add((char)(_n + '0'));

            if(i == maxLen-1 && digit !=0){

                result.Add((char)(digit+ '0'));

            }

        }

        result.Reverse();

        Console.WriteLine(new string(result.ToArray()));

    }

}