public class Program

{

    public static void Main()

    {

        string input = "HI";

​

        int shift = int.Parse("2");

​

        char[] alphabet = new char[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' };

​

        string output_text = "";

​

        char[] input_array = input.ToCharArray();

​

        for (int j = 0; j < input_array.Length; j++)

        {

            for (int i = 0; i < alphabet.Length; i++)

            {

                if (input_array[j] == alphabet[i])

                {

                    input_array[j] = alphabet[(i + shift) % alphabet.Length];

                    break;

                }

            }

        }                    

​

        output_text = new string(input_array);

​

        System.Console.WriteLine(output_text);  

    }

}