while (!q.empty() and need != 0) {
        int v = q.begin()->second;
        q.erase(q.begin());
        for (size_t j=0; j<input[v].friends.size(); ++j) {
            q.insert(make_pair(input[input[v].friends[j]].arrival, input[v].friends[j]));
            maximum = min(maximum, input[input[v].friends[j]].arrival);
            cout << input[v].friends[j] << endl;
            need-=1;
            if (need == 0) break;
        }
    }