The problems are from dreamoon_love_AA and drazil(that's me) from Taiwan, and thanks 9mmlitswe for some discussion. Also we want to thank Zlobober and Gerald for helping us prepare the round, Delinur for translating the statement into Russian, and MikeMirzayanov for Codeforces and Polygon.
This is our first round on Codeforces, we hope you'll find it interesting! Please read all problem statements and discover what the main character dreamoon_love_AA do in those problems for he's really cute =)
Update1 Note this round will be held 1.5hrs earlier than usual Codeforces rounds, so please double check the starting time in your local time.
Update2 Score distribution!
Update3 The contests are over. Congratulations to the winners!
Update4 Editorial can be found here. It's finished by now but it's welcome to tell me if anything can be improved!