Implement the following program in an imperative style and an object-oriented style using any languages you choose provided they have an open-source implementation.
Implement a calendar program that stores the appointments for a one week period. The appointments can occur at anytime during the week, can be of any duration and there can be a variable number of appointments per day. The program should allow the user to add and remove appointments, as well as print the appointments for the whole week or any day within the week.