GOVNO

deque<pair<int,int> >  GET_CONVEX_HULL(){
    vector<pair<int,int> >  arr;
    for(auto [y,x]: Set){
        arr.push_back({x,y});
    }
    ll buffer, xstart, ystart;
    xstart = arr[0].first;
    ystart = arr[0].second;
    sort(arr.begin()+1, arr.end(), [xstart, ystart, &buffer](pair<int,int> a,pair<int,int> b) {
        buffer = VectMultiply(xstart, ystart, a.first, a.second, xstart, ystart, b.first, b.second);
        if(buffer==0) return (a.second-ystart)*(a.second-ystart) + (a.first-xstart)*(a.first-xstart) <
         (b.second-ystart)* (b.second-ystart) + (b.first - xstart) * (b.first - xstart);
        return buffer>0;
    });
    deque<pair<int,int> > ans;
    ll curx = arr[1].first, cury = arr[1].second;
    ll nextx,nexty;
    ll prex = arr[0].first, prey = arr[0].second;
    ans.push_front(arr[0]);
    ans.push_front(arr[1]);
    int index = 1;
    buffer = 0;
    do{
        tie(curx, cury) = ans.front();
        index++;
        tie(nextx,nexty) = arr[index%n];
        //if(index == n) return ans;
        buffer = VectMultiply(prex, prey, curx, cury, curx, cury, nextx, nexty);
        //cout<<"{ "<<prex<<" , "<<prey<<" } { "<<curx<<" , "<<cury<<" } { "<<nextx<<" , "<<nexty<<" } "<<buffer<<" buffer"<<endl;
        if(buffer <= 0) {
             ans.pop_front();
             while(ans.size()>1){
                tie(curx, cury) = ans.front();
                ans.pop_front();
                tie(prex, prey) = ans.front();
                buffer = VectMultiply(prex, prey, curx, cury, curx, cury, nextx, nexty);
                //cout<<"{ "<<prex<<" , "<<prey<<" } { "<<curx<<" , "<<cury<<" } { "<<nextx<<" , "<<nexty<<" } "<<buffer<<" buffer1"<<endl;
                if(buffer>0){
                    ans.push_front({curx, cury});
                    break;
                }
            }
        }
        prex = curx;
        prey = cury;
        curx = nextx;
        cury = nexty;
        ans.push_front({curx, cury});
    } while(index!=n);
    return ans;
}