public void add_last(int i)
        {
            DNODE node = new DNODE(i);

            tail.next = node;
            node.prev = tail;
            tail      = node;
            ++count;
        }
        public void Question3(int loc)
        {
            DNODE temp = head;

            {
                if (loc <= count)
                {
                    for (int i = 1; i <= loc; i++)
                    {
                        temp = temp.next;

                        if (i == loc)
                        {
                            Console.WriteLine("Number at location {0} is: {1}", loc, temp.data);
                        }
                    }
                }

                else
                {
                    Console.WriteLine("Not found");
                }
            }
        }
 public DNODE(int i)
 {
     data = i;
     next = null;
     prev = null;
 }
 public Dlist()
 {
     head = new DNODE();
     tail = head;
 }
 public DNODE()
 {
     next = null;
     prev = null;
 }