using System;

using System.Text.Json;     

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

            var bob1 = new List<int>(){1,2,3};

            object bob2 = null;

            var thing1 = JsonSerializer.Serialize(bob1);

            var thing2 = JsonSerializer.Serialize(bob2);

            //Your code goes here

            Console.WriteLine("Hello, world!");

            Console.WriteLine(thing1);

            Console.WriteLine(thing2);

    }

}