using System;

​

public class Program

{

    public static void Main()

    {

        var triangle = new Triangle();

    }

​

    internal abstract class Shape

    {

        protected Shape()

        {

            PrintName();

        }

​

        protected virtual void PrintName()

        {

        }

    }

​

    internal class Triangle : Shape

    {

        private readonly string _myName;

        public Triangle()

        {

            _myName = "I am a triangle";

        }

​

        protected override void PrintName()

        {

            Console.WriteLine(_myName.ToLower());

        }

    }

}