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class Solution:
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    def smallestChair(self, times: List[List[int]], targetFriend: int) -> int:
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        arrivals = []
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        departures = []
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        for ind, (x, y) in enumerate(times):
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            heappush(arrivals, (x, ind))
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            heappush(departures, (y, ind))
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        d = {}
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        occupied = [0] * len(times)
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        while True:
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            if arrivals and departures and arrivals[0][0] < departures[0][0]:
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                _, ind = heappop(arrivals)
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                d[ind] = occupied.index(0)
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                occupied[d[ind]] = 1
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                if ind == targetFriend:
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                    return d[ind]
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            elif arrivals and departures and arrivals[0][0] >= departures[0][0]:
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                _, ind = heappop(departures)
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                occupied[d[ind]] = 0