class CopyList
{
    private static class Node
    {
        public int data;
        public Node next;
        
        public Node(int d, Node n)
        {
            data = d;
            next = n;
        }
    }

    public static void main(String[] args)
    {
        // Here is a linked list (oldHead --> 1 --> 3 --> 7).
        Node oldHead = new Node(1,new Node(3, new Node(7, null)));

        // Insert code below to copy the list that oldHead points to
        // to a new list pointed to by newHead.
        Node newHead;


        // Insert code below to print both linked lists to the screen.
    }
}