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class SeatManager:
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    def __init__(self, n: int):
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        self.lis = list(range(1, n + 1))
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    def reserve(self) -> int:
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        mini = min(self.lis)
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        self.lis.remove(mini)
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        return mini
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    def unreserve(self, seatNumber: int) -> None:
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        self.lis.append(seatNumber)