I created a video editorial for Problem D : Cases from last Codeforces Round 961 (Div 2)
https://youtu.be/LgxHoy3Aguk?si=XcacblYTS5nIHMf0
I also created a practice contest with easy version of the problem. You can find it here https://codeforces.me/group/7Dn3ObOpau/contest/538630
Is it that big?
it says you are not allowed to view the contest
Updated the link. It should be accessible now.