class Queue(object):
    def __init__(self, items=None):
        if items is None:
            self.a = []
        else:
            self.a = items

    def enqueue(self, b):
        self.a.insert(0, b)

    def dequeue(self):
        return self.a.pop()

    def isEmpty(self):
        return self.a == []

    def size(self):
        return len(self.a)
