Today I am the author of problems. I'm studying in Nizhny Novgorod State University (2 year, Mechanics and Mathematics). I want to thank the staff codeforces for assistance in preparing the contest, and, personally, Artem Rakhov and Maria Belova (for translations of problems into English). Also special thanks to Alexei Shmelev (NNSU) for writing alternative solutions.
P.S. Unfortunately, this round could be in error to register a team. For teams participating in this round will be counted "out of competition", ie, rating of participants does not change. If you register a team by mistake, you can unregister and register in person.
Link to results.
UPD: Tutorials are available.