HOMEWORK 4:  MAIL DELIVERY


NAME:  < insert name >


MISC. COMMENTS TO GRADER:  
This part is optional.  Use it to explain any problems that you know
about.   Be concise. 

OUTLINE THE ORGANIZATION OF YOUR PROGRAM:
Include the main classes and (especially) the algorithm for finding
and inserting a piece of mail.  Explain how you avoid the O(N) search
time (if there are N pieces of mail already) for any particular
insertion.