int time;

unordered_map<int, unordered_set<int>> mp; // Stores followers

unordered_map<int, vector<pair<int, int>>> mp2; // Stores tweets (time, tweetId)

Twitter() {

time=0;

}

void postTweet(int userId, int tweetId) {

mp2[userId].emplace_back(time,tweetId);

time++;

}

vector<int> getNewsFeed(int userId) {

priority_queue<pair<int,int>> pq;

for(auto i: mp2[userId]) pq.push(i);

for(auto i: mp[userId]){

for(auto j: mp2[i]) pq.push(j);

}

vector<int> feed;

int count=10;

while(!pq.empty() && count){

feed.push_back(pq.top().second);

pq.pop();

count--;

}

return feed;

}

void follow(int followerId, int followeeId) {

mp[followerId].insert(followeeId);

}

void unfollow(int followerId, int followeeId) {

mp[followerId].erase(followeeId);

}