using System;

​

public class Program

{

    public static void Main()

    {

        Document document1 = new Document();

        IStorable document2 = new Document();

        Memo document3 = new Memo();

    }

}

​

public interface IStorable

{

    void Read(string fileName);

    void Write(string fileName);

}

​

public interface ISpeak

{

    double DurationOfSpeech

    {

        get;

    }

​

    void Speak();

}

​

public class Document : IStorable, ISpeak

{

    public double DurationOfSpeech

    {

        get

        {

            return 43;

        }

    }

​

    public void Reformat()

    {

        Console.WriteLine("Reformatting the document");

    }

​

    public void Read(string fileName)

    {

        Console.WriteLine($"The file {fileName} has been read");

    }

​

    public void Write(string fileName)

    {

        Console.WriteLine($"The file {fileName} has been written");

    }

​

    public void Speak()

    {

        Console.WriteLine("The method is speaking");

    }

}

​

public class Memo : Document

{

    public string MemoTo

    {

        get;

        set;

    }

​

    public string MemoFrom

    {

        get;

        set;

    }

​

    public DateTime MemoDate

    {

        get;

        set;

    }

}