using System;

public interface IFoo
{
    void A();
}

public class ClassA : IFoo
{
    void IFoo.A()
    {
        Console.Write("S");
    }

    protected void InvokeA(Type type)
    {
        var map = type.GetInterfaceMap(typeof(IFoo));
        map.TargetMethods[0].Invoke(this, null);
    }
}

public class ClassB : ClassA, IFoo
{
    void IFoo.A()
    {
        Console.Write("A");
    }

    public virtual void A()
    {
        InvokeA(typeof(ClassA));
        InvokeA(typeof(ClassB));
        Console.Write("M");
    }
}

public class ClassC : ClassB, IFoo
{
    void IFoo.A()
    {
        Console.Write(" ");
        Console.Write("D");
    }

    public override void A()
    {
        base.A();
        InvokeA(typeof(ClassC));
        Console.Write("U");
    }
}

public sealed class ClassD : ClassC, IFoo
{
    void IFoo.A()
    {
        base.A();
        Console.Write("R");
    }

    public override void A()
    {
        ((IFoo)this).A();
        Console.Write("A");
        B();
    }

    public void B()
    {
        Console.Write("K");
    }
}


class Program
{
    static void Main(string[] args)
    {
        var classD = new ClassD();
        classD.A();
        Console.ReadKey();
    }
}