a) Modify the following code (using two semaphores) so that the two programs P and P2 execute alternatively (i.e., ...,P2P,PPP... with P, being the first to start execution. C2 Begin ParBegin P1, P2 ParEnd End Program Pa: Begin while (true) {1;} End Program Pz: Begin while (true) {C2;} End b) In the previous program, the two programs P, and P2 are executed in such a way fairness is guaranteed. Modify the previous program (using two semaphores) so that the execution order becomes ...,P2P,P2P,P2P,P .....) with P, being the first to start execution