using System;

public class Program

{

    public static void Main()

    {

        var e = Stage.C2;

        switch(e)

        {

            case Stage.A1:

            case Stage.A2:  

            case Stage.A3:  

                Console.Write("A");

                break;

            case Stage.B1:

            case Stage.B2:  

            case Stage.B3:  

                Console.Write("B");

                break;

            case Stage.C1:

            case Stage.C2:  

            case Stage.C3:  

                Console.Write("C");

                break;

            case Stage.D1:

            case Stage.D2:  

            case Stage.D3:  

                Console.Write("D");

                break;

            case Stage.E1:

            case Stage.E2:  

            case Stage.E3:  

                Console.Write("E");

                break;

            default:

                Console.Write("default");

                break;

        }

    }

    public enum Stage{

        A1,

        A2,

        A3,

        B1,

        B2,

        B3,

        C1,

        C2,

        C3,

        D1,

        D2,

        D3,

        E1,

        E2,

        E3

    }

}