class SF5
{
    public static void main(String[] args)
    {
        LL list = new LL();
        list.addFirst(1);
        System.out.println(list.removeFirst());
    }
}
class LL
{
    private class Node
    {
        private Node link;
        private int x;
        public Node(int x)
        {
            this.x = x;
        }
    }
    private Node first = null;
    private Node last = null;
    public void addFirst(int d)
    {
        Node newNode = new Node(d);
        newNode.link = first;
        first = newNode;
    }
    public Node removeFirst()
    {
        Node p;
        p = first;
        if (p == null)
            return p;
        else
        {
            first = first.link;
            return p;
        }
    }
}