Question $1.[50$ pts$]$ In the following code, four processes produce output using the routine "printf" and synchronize using three semaphores $"R","S"$ and $"T."$ Please explain your answers, e$.$g$.,$ use the processes scheduling trace$/$order

Semaphore $R=1,S=3,T=0$;; initialization $*/$

a$)$ How many A and B$\text{'}$s are printed when this set of processes runs?

b$)$ What is the number of D$\text{'}$s that might be printed when this set of processes runs?