abstract class Logger

{

     public void Log(string message)

    {

        Connect();

        Write(message);

        Close();

    }

    public abstract void Connect();

    public abstract void Write(string message);

    public abstract void Close();

}

class TxtLogger : Logger

{

    public override void Connect()

    {

        Console.WriteLine("Txt File is Connected");

    }

    public override void Write(string message)

    {

        Console.WriteLine (DateTime.Now.ToString()+":"+message);

    }

    public override void Close()

    {

        Console.WriteLine("Txt log file is Closed");

    }

}

class XmlLogger : Logger

{

    public override void Connect()

    {

        Console.WriteLine("Xml log file  is Connected");

    }

    public override void Write(string message)

    {

        Console.WriteLine (DateTime.Now.ToString() + ":" + message);

    }

    public override void Close()

    {

        Console.WriteLine("Xml log file is Closed");

    }

}

class MainApp

{

    static void Main()

    {

        Logger logger = null;

        logger = new TxtLogger();

        logger.Log("it is normal");

        Console.WriteLine ("-------------------------------------------");

        logger = new XmlLogger();

        logger.Log("it is normal");

    }

}