Help me to understand the problem

Airlines need to optimize the use of their fleet of aircraft across routes (flight schedules). Given a list of flight schedules, an airline would need to determine the minimum number of aircraft required.

We have to determine the minimum number of aircraft required to support a given set of flight schedules.

I have designed signature as

List<AircraftRoute> = GetAircraftRoutes(List<Flight>)

i am confused with how many number of classes to design

i think there will be only one class which will calculate no of flightes

will it be sufficient ? can anyone help me out with this