import java.util.NoSuchElementException;

public interface LinkedListInterface<E extends Comparable<E>> {
    /**
     * The number of items in the linked list
     * 
     * @return the number of items in the linked list
     */
    int size();

    /**
     * Returns true iff the linked list has no elements
     * 
     * @return true iff the linked list has no elements
     */
    boolean isEmpty();

    /**
     * Get the first element in the linked list
     * 
     * @return the first element in the linked list
     * @throws NoSuchElementException is the list is empty
     */
    E first() throws NoSuchElementException;

    /**
     * The last element in the linked list
     * 
     * @return the last elment
     * @throws NoSuchElementException if the linked list is empty
     */
    E last() throws NoSuchElementException;

    /**
     * Add an element at the end of the list
     * 
     * @param c the element to be added
     */
    void addLast(E c);

    /**
     * Add a element at the front of the list
     * 
     * @param c the Element to be added
     */
    void addFirst(E c);

    /**
     * Remove the first element from the list
     * 
     * @return the first element, or null if the list is empty
     */
    E removeFirst();

    /**
     * Remove the last element from the list
     * 
     * @return the last element, or null if the list is empty
     */
    E removeLast();

    /**
     * Remove the specified element from the list
     * 
     * @param r the element to be removed
     * @return the removed element, or null is the element was not in the list
     */
    E remove(E r);

    /**
     * Find a element in the list by its iD
     * 
     * @param iD
     * @return the found element or null if a match could not be found
     */
    E find(E iD);
}