6 Consider a stack of integers s and a queue of integers o, which are initially empty. Suppose the following operations are performed: pushStack (S, 3) pushStack (S, 12) enqueue (Q, 5) enqueue (Q, 8) popStack (S, x) pushStack (S, 2) enqueue (Q, x) dequeue (Q, y) pushStack (S, x) pushStack (S, y) Answer the following questions. 6.1 What number is at the front end of the queue? 6.2 What number is at the rear end of the queue? 6.3 What number is at the top of the stack? 6.4 What is the value of x? [2 marks]