using System;

public class Program

{

    public static void Main()

    {

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

​

            int a = 1, npm = 10;

​

            while (a <=9)

                if (a == npm )

            {

                Array.Reverse(arr1);

                Console.WriteLine("skip");

            }

            else; 

            {

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

            }

           a++;

        }

    }