using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        ClassA a = new();

        ClassB b = new();

        OhNo no = new();

        List<BaseClass> classes = [a,b,no];

        foreach (BaseClass x in classes) {

            Console.WriteLine(((NumberClass)x).Number);

        }   

    }

}

​

public abstract class BaseClass {

    public virtual string Name => "BaseClass";

}

public abstract class NumberClass : BaseClass {

    public virtual int Number => 0;

}

​

public class ClassA : NumberClass {

    public override string Name => "ClassA";

    public override int Number => 45;

}

​

public class ClassB : NumberClass {

    public override string Name => "ClassB";

    public override int Number => 99;

}

​

public class OhNo : BaseClass {

    public override string Name => "Oh No!";

}

​