¡Buenas, Codeforces!

We are super excited to announce Codeforces Round 1127 (Div. 1, Div. 2), which will start on Oct/11/2026 21:35 (Moscow time) Note the starting time is 4 hours later than the usual. The contest will be split into 2 divisions where you will be given 6 problems and 2 hours to solve them. At least one problem will be interactive so we recommend reading the guide on interactive problems.

Div. 1 score distribution: $$$500 - 1000 - 1250 - 2000 - 2250 - 3500$$$

Div. 2 score distribution: $$$500 - 1250 - 1250 - 1750 - 2000 - 3000$$$

This round is based on the Mexican Olympiad in Informatics (OMI) 2026. All problems were written and prepared by our team of pupils, aka writers, namely jampm, Francisco_Martin, Teto, SopaconK, Remgagagali727, Marckess, and efishel. We hope you enjoy it and maybe learn something about Mexican culture along the way.

The team would like to thank:

cry for their considerate coordination (and ample basement).

All these pupils, aka testers, for their support and great feedback (we love you): SpyrosAliv, AksLolCoding, turska, JoenPoenMan, kevinyang, miniyahirpro, AmShZ, pyoro, Blagoj, br1g, Juanchoki, prvocislo, osvarp, ecnerwala, Argentum47, Keshi, prins, racsosabe, danielrmzkuhn1, 0xor1, temporary1, nik_exists, nifeshe, Edu175, CSQ31, tourist.

Alexdat2000 for translating statements.

ocarima et familia for their many years supporting the Mexican Olympiad in Informatics and pushing us to grow.

MikeMirzayanov & KAN. You know why :)