A certain company wants to improve the rate at which their login system is accessed and you have been
tasked to carry out this project. In this project, you will consider the problem of organizing a collection of
computer user-ids and passwords. Each time a user logs in to the system by entering his or her user-id
and a secret password, the system must check the validity of this user-id and password to verify that this
is a legitimate user. Because this validation must be done many times each day, it is necessary to
structure this information in such a way that it can be searched rapidly. Moreover, this must be a
dynamic structure because new users are regularly added to the system and some users deleted from the