using System;

public class Program

{

    interface IValue

    {       

    }

    class Value : IValue

    {   

    }

    interface IA

    {

        IValue Message { get; }

    }

    interface IAA<T> : IA where T : IValue

    {

        new T Message { get; }

    }

    class A : IA

    {

        public IValue Message => new Value();

    }

    class AA : A, IAA<Value>

    {

        public Value Message => new Value();

    }

    public static void Main()

    {

        Console.WriteLine("Hello World!");

    }

}