Consider the sequence of operations: add(1), add(2), del, add(3), add(4), add(5), add(6), del, del, add(7), del, del. a) Interpreting add and del as Stack operations, push and pop, give an equivalent sequence with no del operations. What would be returned by top after the sequence? b) Do the same, interpreting add and del as Queue operations, enqueue and dequeue. What would be returned by front after the sequence?