Hello, Codeforces!

With great felicity, immense joviality, and unparalleled positivity, we, a team of authors united by our creativity, originality, ingenuity, and curiosity, consisting of omsincoconut, chromate00, ttamx, yse, Marszpace, an individual of mysterious identity, and me, SpyrosAliv, have the distinct opportunity and absolute pleasure to invite you to WorldQuant Round 1 (Codeforces Round 1128, Div. 1 + Div. 2), an event of exceptional quality and remarkable diversity, which will become a reality on Oct/17/2026 17:35 (Moscow time).

You will be presented with 8 problems of varying complexity, difficulty, and subtlety, with exactly 3 hours of availability to demonstrate your ability, capability, adaptability, versatility, productivity, efficiency, accuracy, agility, rationality, and problem-solving proficiency. Some problems may feature a multiplicity of subtasks, providing additional flexibility and accessibility while preserving the overall integrity of the contest.

Of course, with absolute certainty and without any ambiguity, at least one problem will be a communication problem, introducing an additional layer of interactivity, connectivity, and unpredictability. Therefore, to maximize your probability of success and minimize the possibility of unnecessary challenges, we emphasize the necessity and priority of reading the guide for communication problems before the contest.

Special thanks to the following people for helping make this round a reality:

• flamestorm, simplelife, ItzsleepyXD for proposing problems that are not ultimately used in the round.
• Um_nik for pre-reviewing the problemset;
• Proof_by_QED for being the best coordinator of all time;
• The testers: EvenImage, nifeshe, A_G, __baozii__, Error_Yuan, turska, Stathis, Mentholzzz, cry, Timosh, coder3000, ReverseFlash081, Argentum47, Hori, wakanda-forever, Lxnsr._th, coder3000, cowthecow, Borhom, blackslex,samsoom, nik_exists, Mysticmage45, SkyMagic, Teto.
• Alexdat2000 for translating statements to Russian;
• MikeMirzayanov and KAN for Polygon and Codeforces platforms.
• and last but not least, You for participating!

Score distribution:

And now, a few words from the sponsor!

Hello, Codeforces community!

We are happy to welcome you to the WorldQuant Round 1 and proud to support a platform where so many talented programmers learn and compete.

WorldQuant is a global quantitative asset management firm. Founded in 2007, WorldQuant develops and deploys systematic financial strategies across a broad range of asset classes and global markets. Our teams work collaboratively to drive the production of high-quality predictive signals (alphas) and financial strategies — the foundation of a balanced, global investment platform.

At WorldQuant Armenia, talented people with diverse backgrounds, including participants and prize winners of competitions like IMC, IMO, ICPC, and IPhO, work together to tackle challenging problems. We value curiosity, teamwork, and the passion to learn, creating an environment where people can grow, share ideas, and achieve great things together.

We are looking for talented individuals to join our team at WorldQuant Armenia in the following roles:

• Quantitative Researcher
• Senior Python Engineer
• AI Software Developer

Please note that relocation to Armenia is required, and WorldQuant can provide assistance with relocation for successful candidates.

To apply, fill in the application form.

The winners will receive our exclusive branded swag:

• Hoodies + T-shirts for the top 5
• T-shirts for participants ranked 6–30

Whether you are competing for the top places or simply challenging yourself to improve, we hope you have a great time!

PS We reserve the right to apply strict compliance checks when finalizing the results in order to prevent unfair participation and rule violations.

Please note that prize delivery to certain countries, states, provinces, or territories may be subject to applicable sanctions, trade restrictions, or other legal requirements. We will make every reasonable effort to deliver prizes to all eligible winners, subject to any restrictions that may apply.