set<pair<int,int> >hi,;
set<pair<int,int>,greater<pair<int,int> > >lo;
void balance()
{
     while(hi.size() > lo.size())
     {
         lo.insert(hi.begin());
         hi.erase(hi.begin());
     }
    while(lo.size()-1  > hi.size() )
    {
        hi.insert(lo.begin());
        lo.erase(lo.begin());
    }
}
int activityNotifications(vector<int> expenditure, int d) {


    for(int i=0;i<expenditure.size();i++)
    {
        lo.insert( make_pair(expenditure[i],i) );
        balance();

        if(i>=d)
        {
            auto it = lo.lower_bound( make_pair(expenditure[i-d],i-d) );
            if(it!=lo.end()) lo.erase(it);
            else {
                auto it = hi.lower_bound( make_pair(expenditure[i-d],i-d) );
                if(it!=hi.end()) hi.erase(it);
            }
        }
        balance();
    }

}