public class polygonlist
{
public polygonlink head;
public polygonlink tail;

public polygonlist()
    {
	head = null;
	tail = null;
    }

public void insert(polygon p)
    {
	if(p == null)
	    return;
	if(head == null)
	    {
		head = new polygonlink(p);
		tail = head;
	    }
	else
	    {
		tail.next = new polygonlink(p);
		tail = tail.next;
	    }
    }
}