Statement

In his never-ending quest for improvements of the Italian training website, William decided to rewrite the chat system from scratch. This system allows students to communicate with one another in real time. A key component in any chat system is the "recent chat list". This list shows all the names of people who have been contacted at least once, sorted by last contact time, that is: in the top there will be the user that has been most recently contacted (no other user has been contacted yet), in the bottom there is the user that has been least recently contacted (no other user was last contacted before). Of course, this final list cannot have duplicates by construction. Help William write the "recent chat list" component. You will be given the list of people contacted, from the first person contacted to the last. There can be multiple entries in this list (when a person is contacted multiple times). Print the order in which those people will appear in the final list.