Hello, Codeforces!

I'm very glad to invite you to Codeforces Round 639 (Div. 1) and Codeforces Round 639 (Div. 2). This contest will take place on 06.05.2020 17:35 (Московское время). In both divisions, you will have 2 hours 15 minutes to solve 6 problems. The score distribution will be announced closer to the start of the contest.

Of course, this round would not be possible without the help of many people, who I'd like to thank:

• isaf27, for coordinating this round, helping with solution ideas.
• My ICPC teammates Kuroni and strongoier, and coach cnh355, for encouraging me to pursue competitive programming. In particular, I'd like to thank Kuroni for being so spectacularly bad that a barely-orange user like myself actually has a place on our team.
• 300iq, antontrygubO_o, Ari, ffao, fpc_coder, gamegame, Kuroni, entropy07, McDic, richzli, and VilgefortzOfRoggeveen for testing and providing valuable feedback.
• MikeMirzayanov for providing the Codeforces and Monogon Polygon platforms.

I've done my best to write clear problem statements and strong pretests. Don't forget to read all problems, and I hope you enjoy the round. Good luck!

Because I know you all have so many questions, I have compiled an FAQ:

• Q: Is it rated?
• A: Yes.