A.rear.next=p;rear=p;B.front=front.next;p=front;C.rear=p;rear.next=p;D.p=front;front=front.next;
A.p=front;front=front.next;B.front=front.next;p=front;C.rear.next=p;rear=p;D.rear=p;rear.next=p;
A.rear.data;B.front.data;C.rear.next.data;D.front.next.data;