---

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp2   {
    internal class Bs    {
        internal int i;
        internal virtual void Print() { Console.WriteLine("Bs::Print();}");  }
    }

    internal class Drv : Bs //extends <=> :
    {
        internal int j;
        internal override void Print() { Console.WriteLine("Drv::Print();}"); }
    }
    internal class Program    {
        static void Main(string[] args)        {
            Bs bs = new Bs(); // Bs* pBs = new Bs(); 
            bs.Print();
            Drv drv = new Drv();
            drv.Print();

            //bs = drv;
            //bs.Print();
            //drv = bs;
            //drv.Print();
        }
    }
}