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class SeatManager {
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  PriorityQueue<Integer> pq;
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  int count;
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  public SeatManager(int n) {
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    count = 1;
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    pq = new PriorityQueue();
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  }
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  public int reserve() {
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    if (pq.size() == 0) return count++;
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    return pq.poll();
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  }
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  public void unreserve(int seatNumber) {
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    pq.add(seatNumber);
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  }
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}