Hello, Codeforces!

We are happy to invite you to the XIII UnB Contest Mirror on Nov/04/2025 20:00 (Moscow time). This contest was originally held at University of Brasília, during our annual University Week.

This contest is a Codeforces Gym, and therefore is NOT an official Codeforces Round and is NOT rated.. The contest will follow standard ICPC rules.

The problems were created and prepared by:

• Arthur Botelho (me)
• Eduardo Freire (duduFreire)
• Eduardo Quirino (cebolinha)
• Emerson Cruz (emershowjr02)
• Maxwell Oliveira (Maxwell01)
• Pedro Avila Beneveli (PedroPacoca)
• Wilson Guimarães (Vilsu)
• Professor Daniel Porto (dporto)
• Professor Edson Alves (edsomjr)
• Professor Guilherme Ramos (gnramos)
• Professor Jeremias Gomes (j3r3mias)

Also, we would like to thank:

• Our problem reviewers and testers: Guilherme Rocha (TheRockRocha), Lucas Gabriel (lucasg05), Nikolle Licá (june16th) and Ruan Petrus (MagePetrus);
• Víctor Lamarca (VLamarca) for contributing to the preparation of the problems.
• DOM Judge team for the platform used in the on-site contest;
• dario2994 for the brilliant pol2dom tool;
• MikeMirzayanov for the amazing Codeforces and Polygon platforms.

Most of the problems are aimed at those who are starting their journey in competitive programming. However, we also included a few problems we believe will be an interesting challenge for more experienced participants, such as finalists of ICPC Regionals.

Good luck to all participants!

Note: if you participated in the on-site contest, please don't make any comments regarding the problems in this blog. As soon as the Mirror finishes, we will publish an editorial blog — you may discuss the problems there.