$($b$)$ Write a Java class to control access to a classroom of $100$ students using semaphores, with a first$-$come, first$-$served guarantee that students who arrive first are allowed to access the classroom before late arriving students. Your class should have two methods EnterClass and LeaveClass.

$(15$ marks$)$

$($c$)$ Write a main program to test part $2,$ generating $30$ students every $5$ minutes. You do not need to write the Student thread class.