A barbershop is divided into two rooms. The waiting room has n chairs, and the work room only has the barber chair. When the waiting room is empty, the barber goes to sleep in the barber chair.

If a customer comes in and the barber is asleep, he knows its his turn to get his hair cut. So he wakes up the barber and takes his turn in the barber chair. But if the waiting room is not empty, the customer must take a seat in the waiting room and wait his turn.

Write and submit the source code of a Java program that will coordinate the barber and his customers.