Detective Boev

using System;


class DetectiveBoev
{
    static void Main()
    {
        string secretWord = Console.ReadLine();
        string encryptedWord = Console.ReadLine();
        int secretWordResult = Mask(secretWord, secretWord.Length - 1);
        int secretWordToMask = ResultMask(secretWordResult);
        Console.WriteLine(EncryptMsg(encryptedWord, secretWordToMask));
    }


    private static string EncryptMsg(string msg, int divide)
    {
        string msgResut = string.Empty;
        for (int i = msg.Length - 1; i >= 0; i--)
        {
            char check = msg[i] % divide == 0 ? (char)(msg[i] + divide) : (char)(msg[i] - divide);
            msgResut += check;
        }
        return msgResut;
    }

    private static int Mask(string mask, int lenght)
    {
        if (lenght == 0)
        {
            return mask[0];
        }
        return mask[lenght] + Mask(mask, lenght - 1);
    }

    private static int ResultMask(int result)
    {
        int returnNumber = 0;
        int singleDigit = 0;
        while (result != 0)
        {
            returnNumber += result % 10;
            result /= 10;
        }
        if (returnNumber > 9)
        {
            while (returnNumber > 9)
            {
                singleDigit += returnNumber % 10;
                returnNumber /= 10;
                singleDigit += returnNumber;
            }
            return singleDigit;
        }
        else
        {
            return returnNumber;
        }
    }
}