import java.util.*;

class BasicLinkedList <E> implements ListInterface <E> {

	// Data attributes
	protected ListNode <E> head = null;
	protected int num_nodes = 0;

	// Return true if list is empty; otherwise return false.
	public boolean isEmpty() { 
		return (num_nodes == 0); 
	}

	// Return number of nodes in list.
	public int size() { 
		return num_nodes; 
	}

	// Return value in the first node.
	public E getFirst() throws NoSuchElementException {
		if (head == null) 
			throw new NoSuchElementException("can't get from an empty list");
		else return head.getElement();
	}

	// Return true if list contains item, otherwise return false.
	public boolean contains(E item) {
		for (ListNode <E> n = head; n != null; n = n.getNext())
			if (n.getElement().equals(item)) return true;

		return false;
	}

	// Add item to front of list.
	public void addFirst(E item) {
		head = new ListNode <E> (item, head);
		num_nodes++;
	}

	// Remove first node of list.
	public E removeFirst() throws NoSuchElementException {
		ListNode <E> ln;
		if (head == null) 
			throw new NoSuchElementException("can't remove from an empty list");
		else { 
			ln = head;
			head = head.getNext();
			num_nodes--;
			return ln.getElement();
		}
	}

	// Print values of nodes in list.
	public void print() throws NoSuchElementException {
		if (head == null)
			throw new NoSuchElementException("Nothing to print...");

		ListNode <E> ln = head;
		System.out.print("List is: " + ln.getElement());
		for (int i=1; i < num_nodes; i++) {
			ln = ln.getNext();
			System.out.print(", " + ln.getElement());
		}
		System.out.println(".");
	}
}