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 >= self.size:
            self.pointer = 0
    def average(self):
        value = 0
        length = 0
        for i in self.queue:
            if i != None:
                value += i
                length += 1
        if length == 0:
            return 0
        return value / length