Exercise: we have circular buffers of size n. The buffers are numbered from 0 to n-1, so the buffer following buffer n-1 is 0. Solve the following synchronization problem with semaphores and wait/signal operations. There are two processes: producer (repeatedly writes to buffers, one at a time) and consumer (repeatedly reads from buffers, one at a time). Initially the buffers are empty. Reading and writing start from buffer 0, then 1,2,...,n-1,0,1... Reading a buffer makes it empty. The consumer cannot read an empty buffer. The producer cannot write to an occupied buffer.