Write an application class PlaneApp that implements the seating reservation program.

The class PlaneApp should be able to support the following:

(1) Show the number of empty seats

(2) Show the list of empty seats

(3) Show the list of customers together with their seat numbers in the order of the seat numbers

(4) Assign a customer to a seat

(5) Remove a seat assignment

The menu should also contain option (6) (i.e. quit) for terminating the program. After the user

selects a particular option, the corrsponding operation will be executed. If the selected option is

not (6), then the program shows the menu for user selection again. This application does not need

to save data into a file between runs.