An airport is developing a computer simulation of air-traffic control that handles events such as landings and takeoffs. Each event has a time stamp that denotes the time when the event will occur. The simulation program needs to efficiently perform the following two fundamental operations:

• Insert an event with a given time stamp (that is, add a future event).

• Extract the event with smallest time stamp (that is, determine the next event to process).

Which data structure should be used for the above operations? Why?