$7)$ Consider the following pseudocode for $5$ processes. The processes are executing on a uniprocessor system. The

processes share a counting semaphore S initialized to $4.$ Assume semaphore implementation without busy waiting

and the S$->$list is implemented as a FIFO queue. The value of S can become negative also. Assume that whenever a

process gets blocked because of wait$()$ execution, another process is scheduled.

P$1$ P$2$ P$3$ P$4$ P$5$

wait$($S$)$;

print $$A$$;

signal$($S$)$;

wait$($S$)$;

print $$B$$;

wait$($S$)$;

signal$($S$)$;

print $$A$$;

wait$($S$)$;

wait$($S$)$;

print $$B$$;

print $$A$$;

signal$($S$)$;

signal$($S$)$;

The processes are scheduled in the following order: P$2,$ P$3,$ P$1,$ P$2,$ P$3,$ P$4,$ P$1,$ P$3,$ P$4,$ P$5,$ P$1,$ P$3,$ P$5,$ P$1,$ P$3,$ P$4.$

Explain clearly the operations carried out by each process, the contents printed and the value of S in each step.