4.30 The Unisex Bathroom. Suppose there is one bathroom in your department. It can be used by both men and women, but not at the same time. (a) Develop a solution to this problem. First specify a global invariant, then develop a solution using semaphores for synchronization. Allow any number of men or women to be in the bathroom at the same time. Your solution should ensure the required exclusion and avoid deadlock, but it need not be fair