(Translation: Hello)

We are very happy to invite you to take part in our contest, Codeforces Round 666 (Div. 1) and Codeforces Round 666 (Div. 2). The contest starts on 30.08.2020 17:35 (Московское время) and lasts 2 hours. In both divisions, there will be 5 problems for you to solve.

The problems were authored and prepared by JettyOller, DatVu, MofK, and me.

We are very grateful and would like to sincerely thank the following people for their assistance in preparing the round:

• 300iq for coordinating our round and for reviewing and helping us with the problems.

• minhtung04042001, TomOwO, SeehtEntity for their problem ideas and for helping us prepare the problemset.

• EternalFire, SucculentLover, DeadlyCritic, coderz189, VietCT, EdBarge, hugopm, Combi, TechNite, thenymphsofdelphi, mdinh, Tech.Maniac, Umi, quanpham0805, user202729_, Jarjit_sigh, Kuroni, dorijanlendvaj, neko_nyaaaaaaaaaaaaaaaaa, Jatana for testing the problems and providing helpful feedback and suggestions.

• MikeMirzayanov for the amazing platforms Codeforces and Polygon.

Finally, we would like to thank all of you for participating in the contest!

We have spent many months to brainstorm ideas, ended up discarding most of them, and finally chosen our best ideas to compose together this contest, so we hope you will enjoy our round! (and hope the Devil's Number won't haunt our round XD)

Good luck, have fun!

The score distribution will be announced later.