class Queue:
    def __init__(self, events=None):
        self.events = [] if events is None else events
        self.records = []
    def enqueue(self, key, cents):
        if isinstance(cents, bool) or not isinstance(cents, int) or cents <= 0:
            raise TypeError('positive integer cents required')
        for previous_id, amount in self.records:
            if previous_id == key:
                if amount != cents:
                    raise ValueError('conflicting amount')
                return 'duplicate'
        self.events.append({'id': key, 'cents': cents})
        self.records.append((key, cents))
        return 'queued'