Polymorphism and Method Hiding question - create object collection to print all class method

class First
{
    public virtual void Hello()
    {
        Console.Write("First \n");
    }
}
class Second : First
{
    public override void Hello()
    {
        Console.Write("Second \n");
    }
}
class Third : First
{
    public new void Hello()
    {
        Console.Write("Third \n");
    }
}

static void Main(string[] args)
{
     List<First> lst = new List<First>();
     lst.Add(f);
     Second s = new Second();
     lst.Add(s);
     Third t = new Third();
     lst.Add(t);

     foreach (First obj in lst)
     {
         obj.Hello();
     }
     Console.ReadKey();
 }