import heapq


class Twitter:
    def __init__(self):
        self.time = 0
        self.tweets = {}
        self.follows = {}

    def postTweet(self, userId, tweetId):
        self.time += 1
        if userId not in self.tweets:
            self.tweets[userId] = []
        self.tweets[userId].append((-self.time, tweetId))

    def getNewsFeed(self, userId):
        heap = []
        if userId in self.tweets:
            heap.extend(self.tweets[userId][-10:])
        if userId in self.follows:
            for v in self.follows[userId]:
                if v in self.tweets:
                    heap.extend(self.tweets[v][-10:])
        heapq.heapify(heap)
        res = []
        while heap and len(res) < 10:
            res.append(heapq.heappop(heap)[1])
        return res

    def follow(self, followerId, followeeId):
        if followerId == followeeId:
            return
        if followerId not in self.follows:
            self.follows[followerId] = set()
        self.follows[followerId].add(followeeId)

    def unfollow(self, followerId, followeeId):
        if followerId in self.follows and followeeId in self.follows[followerId]:
            self.follows[followerId].remove(followeeId)


if __name__ == "__main__":
    tw = Twitter()
    tw.postTweet(1, 5)
    print(tw.getNewsFeed(1))
    tw.follow(1, 2)
    tw.postTweet(2, 6)
    print(tw.getNewsFeed(1))
    tw.unfollow(1, 2)
    print(tw.getNewsFeed(1))