int freeSeats = n;
sem waitingRoom = 1; // mutex for the waiting room counter and the priority customer counter
sem customerReady = 0; // the queue for the waiting customers
sem barberReady = 0; // the availability of the barber
int waitingPriorityCustomers = 0; // number of waiting priority customers

process RegularCustomer[1:m] {
    while (true) {
        P(waitingRoom); // acquire lock for waiting room 

        // check if there are free seats, other leave
        if (freeSeats > 0) {
        // wait for the barber to be ready
        freeSeats := freeSeats - 1; // take a seat
        V(customerReady); // signal to the barber that a customer is waiting
        V(waitingRoom); // release the look, before we are waiting for the barber to be ready
        P(barberReady); // wait for the barber to pick up the customer
        
        while (waitingPriorityCustomers > 0) { // the barber has the look for the waiting room, therefore it safe to check this variable
             // release the lock on the room
            V(barberReady);
            V(waitingRoom); // we need to free to the lock that we got from the barber, before we wait again
            P(barberReady);
        }

        // customer gets a hair cut
        }

        V(waitingRoom); // customer leaves the waiting room and releases the look OR we need to free the lock that we got from the barber
    }
}

process PriorityCustomer[1:t] {
    while (true) {
        P(waitingRoom); // acquire lock for waiting room 
        // check if there are free seats, otherwise leave
        if (freeSeats > 0) {
        // wait for the barber to be ready
        freeSeats := freeSeats - 1;
        waitingPriorityCustomers := waitingPriorityCustomers + 1
        V(customerReady); // signal to the barber that a customer is waiting
        V(waitingRoom); // release the look, before we are waiting for the barber to be ready
        P(barberReady); // wait for the barber to pick up the customer
        waitingPriorityCustomers := waitingPriorityCustomers - 1 // barber has the look for the waiting room, therefore it safe to manipulate this variable
        // customer gets a hair cut
        }
        V(waitingRoom); // customer leaves the waiting room and releases the look OR we need to free the lock that we got from the barber

    }
}


process Barber {
    while (true) {
        // sleeps if there a no customers
        // if customer available then cut hairs
        P(customerReady);
        P(waitingRoom); // lock the waiting room
        freeSeats := freeSeats + 1;
        V(barberReady);
        // We don't free the lock but pass it back to the customer
        // cut the hairs of the customer
    }
}