. Implement a priority queue (priorities will be integers) using a doubly linked list. Assume that the smaller the integer the higher priority. The main operations of the priority queue are:

add (n): inserts priority n.

max: returns (but does not delete) the highest priority.

removeMax(): removes a highest priority.

Write a tester class and name it Main. You are expected to structure the code as indicated in the UML class diagram:

Main

+static void main(String[] args)

+Main()

PriorityQueue

-Node first

-Node last

+PriorityQueue()

+boolean isEmpty()

+void add(int x)

+int max()

+void removeMax()

Node

-int info

-Node next

-Node prev

+Node()

+void setInfo(int i)

+void setNext(Node p)

+setPrev(Node p)

+int getInfo()

+Node getNext()

+Node getPrev()