Valerie is deciding on her schedule for next semester. She must take each of the following classes: English 102, Music 101, History 102, and Math 120. If there are 16 sections of English 102, 10 sections of Music 101, 12 sections of History 102, and 13 sections of Math 120, how many different possible schedules are there for Valerie to choose from? Assume there are no time conflicts between the different classes.