encryption

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int l;
            string[] abc = new string[26] { "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z" };
            Console.WriteLine("Enter the Value of your encryption");
            int num = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine("Your are encrypting by " + num);
            Console.WriteLine("Enter word to encrypt");
            string word = Console.ReadLine();

            char[] characters = word.ToCharArray();
            l = characters.Length;


            int repetition = 0;
            do
            {
                char letter = characters[repetition];
                int number = Convert.ToInt32(characters[repetition]);
                number = number - 97;
                number = number + num;
                while (number > 25)
                {
                    number = number - 26;
                }
                while (number < 0)
                {
                    number = number + 26;
                }


                Console.Write(abc[number]);



                repetition++;
            }



            while (repetition < l);


            Console.WriteLine("");
        }
    }
}