using System;

public class Program

{

    public static void Main()

    {

        string[] arr1 = new string[] { "A", "B", "C", "D" };

            int i = 1, npm = 3;

            while (i <= 10)

            {

                if (i == npm)

                {

                    Array.Reverse(arr1);

                    Console.WriteLine(" ");

​

                }

                else

                {

                    Console.WriteLine("kelas" + i + "." + arr1[0] + "\t" + "kelas" + i + "." + arr1[1] + "\t" + "kelas" + i + "." + arr1[2] + "\t" + "kelas" + i + "." + arr1[3]);

                }

                i++;

            };

    }

}