using System;

using System.Linq;

using System.Text;

using System.Text.RegularExpressions;

​

namespace FindSecret

{

    public class Program

    {

        public static void Main(string[] args)

        {

            String numbers = args[1];

            int len = Int32.Parse(numbers.Substring(0, 1));

​

            String payload = numbers.Substring(1);

            payload = new String(payload.Reverse().ToArray());

​

            Regex regex = new Regex(".{1,2}");

            Match match = regex.Match(payload);

​

            String alphabet = "абвгдеёжзийклмнопрстуфхцчшщъыьэюя";

            StringBuilder result = new StringBuilder();

            while (match.Success)

            {

                char ch = alphabet[Int32.Parse(match.Value) - len];

                result.Append(result.Length == 0 ? Char.ToUpper(ch) : ch);

                payload = payload.Substring(match.Index + match.Length);

                match = regex.Match(payload);

            }

​

            Console.WriteLine(result.ToString());

        }

    }

}