static void Main(string[] args)
{
LinkedList <int> list = new LinkedList <int>();
list.AddFirst(1);
list.AddFirst(3);
list.AddLast(2);
list.AddAfter(2, 5);
list.AddAfter(2, 6);
list.AddBefore(5, 4);
list.PrintListForward();
Console.WriteLine("----------------------");
list.PrintListBackward();
//list.RemoveFirst();
//for (int i = 0; i < list.Count; i++)
//{
// Console.WriteLine(list.ValueAt(i));
//}
}