def lastStoneWeight(stones):
stones = [-s for s in stones]
heapq.heapify(stones)
while len(stones) > 1:
first = heapq.heappop(stones)
second = heapq.heappop(stones)
if second > first:
heapq.heappush(stones, first - second)
stones.append(0)
return abs(stones[0])