class circular_queue:
    def __init__(self, size):
        self.size = size
        self.queue = []
        for i in range(self.size):
            self.queue.append(None)
        self.pointer = 0

    def add(self, value):
        self.queue[self.pointer] = value
        self.pointer += 1
        if self.pointer > 49:
            self.pointer = 0

    def average(self):
        queue = self.queue
        while None in queue:
            queue.remove(None)
        if len(queue) == 0:
            return 0
        return sum(queue) / len(queue)