Tracking_interval

class tracker_inter
{
    public:
        set<pair<int, int>> forbidden;

        int clear()
        {
            forbidden.clear();
            return 0;
        }

            bool inter_check(int st, int endi)
        {
            auto itr = forbidden.upper_bound({st, st});
            if(itr==forbidden.end() || itr->first>endi)
            {
                if(itr==forbidden.begin() || prev(itr)->second<st)
                {
                    return 0;
                }
            }
            return 1;
        }

        int pt_remove(int stuff)
        {
            if(!this->inter_check(stuff, stuff))
            {
                return 0;
            }
            pair<int, int> previ = *prev(forbidden.upper_bound({stuff, 1e9}));
            forbidden.erase(previ);

            if(previ.first<=stuff && previ.second>=stuff)
            {
                pair<int, int> insi1 = {previ.first, stuff-1}, insi2 = {stuff+1, previ.second};
                if(insi1.first<=insi1.second)
                {
                    forbidden.insert(insi1);
                }
                if(insi2.first<=insi2.second)
                {
                    forbidden.insert(insi2);
                }
            }
            return 1;
        }

        int pt_add(int stuff)
        {
            if(this->inter_check(stuff, stuff))
            {
                return 0;
            }
            pair<int, int> previn = {stuff, stuff};
            if(!forbidden.empty() && forbidden.upper_bound({stuff, 2e9})!=forbidden.begin())
            {
                previn = *prev(forbidden.upper_bound({stuff, 2e9}));
            }
            if(previn.second==stuff-1)
            {
                forbidden.erase(previn);
                previn.second++;
            }
            else
            {
                previn = {stuff, stuff};
            }
            forbidden.insert(previn);
            if(next(forbidden.find(previn))!=forbidden.end())
            {
                auto thing = *next(forbidden.find(previn));
                if(thing.first==previn.second+1)
                {
                    forbidden.erase(thing); forbidden.erase(previn);
                    previn.second = thing.second;
                    forbidden.insert(previn);
                }
            }
            return 1;
        }
};