using System;

using System.Collections.Generic;

​

public class Base

{

    protected int ID {get;set;}

}

​

public class A : Base

{

    public int A_ID {get;set;}

}

​

public class B: Base

{

    public int B_ID {get;set;}

}

​

public class Program

{

    public static void Main()

    {

        var bar = new Dictionary<string, Base>();

        var objA = new A();

        objA.A_ID = 1;

        var objB = new B();

        objB.B_ID = 2;

        bar.Add("A", objA);

        bar.Add("B", objB);

        Console.WriteLine($"A = {((A)bar["A"]).A_ID}");

        Console.WriteLine($"B = {((B)bar["B"]).B_ID}");

    //  Console.WriteLine($"B = {bar["A"].A_ID}");

    }

}