using System;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Hashtable hash = new Hashtable();

        hash.Add(1, "test");

        var o = new { name = "test", rollNo = "24", standard = new { name = "test" } };

        var o2 = new { name = "test", rollNo = 24, standard = new { name = "test" } };

        var o1 = new { name = "test1" };

        hash.Add(o, new { name = "test", rollNo = "24" });

        hash.Add(o2, new { name = "test", rollNo = "24" });

        foreach(DictionaryEntry de in hash) 

        {

            Console.WriteLine($"{de.Key} => {de.Value}");

        }

        // Dictionary

        Dictionary<int, string> d = new Dictionary<int, string>();

    }

}