using System;

public class Program

{

    public static void Main()

    {

        Person person = new Person();

        Tiger tiger = new Tiger();

        Robot robot = new Robot();

        Working(robot);

        Working(tiger);

        Working(person);

    }

    public static void Working(IWorker worker)

    {

        try

        {

            worker.DoWork();

        }

        catch(Exception ex)

        {

            Console.WriteLine(ex.Message);

        }

    }

}

​

public class Person : IWorker

{

    public void DoWork()

    {

        Console.WriteLine("I'm a person");

    }

}

​

public class Robot : IWorker

{

    public void DoWork()

    {

        Console.WriteLine("I'm a robot");

    }

}

​

public abstract class Animal : IWorker

{

    public void DoWork()

    {

        throw new NotImplementedException();

    }

}

​

public class Tiger : Animal

{

}

​

public interface IWorker

{

    void DoWork();

}

​