using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        Dictionary<A, int> dict = new Dictionary<A, int>();

        A a1 = new A();

        a1.B = "Hi";

        A a2 = new A();

        a2.B = "Hello";

        dict.Add(a1, 0);

        dict.Add(a2, 0);

        for (int i = 0; i < 10; i++)

        {

            dict[a1]++;

            dict[a2]++;

            if (i == 5)

                a1.B = "New!";

        }

        Console.WriteLine(dict[a1]);

        Console.WriteLine(dict[a2]);

        Console.WriteLine("Hello World");

    }

    class A

    {

        public string B {get; set;}

        public override int GetHashCode()

        {

            return 300 + B.GetHashCode();

        }

    }

}