def length(q):
    """Returns number of waiting customers"""
    return len(q)


def show(q):
    """SHOW queue: print list of waiting customers.
    Customer waiting longest
    are shown at the end of the list."""
    print(q)


def add(q, name):
    """Customer with name 'name' joining the queue"""
    q.insert(0, name)


def next_(q):
    """Returns name of next customer to serve, removes
    customer from queue"""
    next_customer = q.pop()
    return next_customer


q1 = []
q2 = []

add(q1, "Peter")
add(q1, "Mary")
add(q2, "Paul")