Pls help CNVX4HUL

Can somebody pls explain this question?
What I understood is, we first have to generate all subsequence of points in O(n*n) time then for each we have to find convex hull in O(nlogn) and if it has four vertices then that subsequence will be compact convex hull, we will keep doing and adding it to ans

@admin @errichto @gennady.korotkevich @tourist1256 @uwi @ram_jamuria

I will see and reply, don’t worry try more hard questions.

thanks for your kind reply to my post