How Sirius and nepotism ruined the biggest Russian olympiad Hello, Codeforces! Yesterday there was an important precedent for the competitive programming: the school stage of the Russian National Olympics in Informatics (I will call it ROI) has completely failed. The testing system could not select the language, it did not test or save submissions during the whole contest, and the organizers had to rewrite the rules right during the Olympiad... The reason for this is not new to our country — nepotism and incompetence. I was a volunteer at one of the schools where the stage was held, and I can tell you how it all happened. ### The problem with online judges Previously, the school stage was decentralized: each region came up with its own problems and **selected the testing system that was convenient for it**. Sometimes this caused "screw-ups", sometimes there were complaints about the unequal complexity of the problems, but in general the system worked. At some point, Moscow experts decided that this would not work, and last...

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LI2 Contests Announcement — Free Programming Course Hi everyone! I'm thrilled to invite you to the **LI2 Contest — free collection of high-quality contests to master every topic** — here, on Codeforces! [Group Link! Click here!](https://codeforces.me/group/jtU6D2hVEi/blog) ### Current avialibale list of topics: Loops; Prefix Sums; Sortings; Binary Search; Recursion; Sweepline; Two Pointers; Linear Data Structers (stack, queue, etc); Graphs, DFS, BFS; Dynamic Programming; DSU; Shortest Paths; Minimum Spanning Tree; Greedy; ... ### Why this course? I believe that finding high-quality problems is the hardest part of practice, especially when you are only getting your feet wet with competitive programming. There are many lectures and articles, but not so many open collections of problems for each topic. ### Time-tested I guarantee you that this course is time-tested, **I used it myself**. LI2 is short for Boarding Lyceum №2 in Kazan — the school I study in. So we've been using this course for...

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# Less than 2 hours left until the Sirius Qualification Round! Register now! # Less than 2 hours left until the Sirius Qualification Round! Register now! **[Prizes RF Only / Statements EN & RU]** ### ⚠️ NOTICE FOR INTERNATIONAL USERS All problem statements will be fully available in both English and Russian! You are more than welcome to participate and solve the problems. Please note that physical prize delivery is strictly limited to the Russian Federation via Ozon, but everyone can compete for fun, rating, and practice! --- Good day, dear Codeforces users! This is a reminder that in **less than 2 hours (at 17:35 Moscow time, UTC+3)**, the Qualification Stage of our contest series based on Sirius Educational Centre problems will begin! --- ### High Chance to Win a Prize! Right now, **the registration activity is VERY low**. This means competition is minimal, and it will be **extremely easy to grab the prizes** in the final round! Don't miss this perfect opportunity. **IMPORTANT RULE:** Users who do not participate in today's qualif...

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[Prizes RF Only / Statements EN & RU] Prizes from Sirius Educational Centre: IOI-format Contest! # [Prizes RF Only / Statements EN & RU] Prizes from Sirius Educational Centre: IOI-format Contest! ### ⚠️ NOTICE FOR INTERNATIONAL USERS **Good news: All problem statements will be fully available in both English and Russian! You are more than welcome to participate and solve the problems. Please note that physical prize delivery is strictly limited to the Russian Federation via Ozon, but everyone can compete for fun and practice!** --- Good day, dear Codeforces users! We are glad to present you a contest that is fully identical to the selection process for the computer science educational program at the Sirius Educational Centre. Over the course of three weeks, exciting problem sets await you. The top participants will receive prizes personally from me and the Sirius Educational Centre! --- ### IMPORTANT: Participation Restriction **We kindly request those who have already participated in the official selection for the "Informatics. Regions" program at Sirius: pl...

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ICPC NEF и ВКОШП 2025 <img src="/predownloaded/19/27/19278d91460396a7175730146d64a7a18467b1a3.jpg" align="right" style="height: 230px; margin: 10px;" alt="NEF 2024"> Hi, Codeforces! December is the perfect time to wrap up the year, and we’re happy to invite you to follow the final stages of the most important school and student team competitions in competitive programming. Mark your calendars: from December 15 to 17, the 26th Russian Team Olympiad in High School Programming Contest and the ICPC Northern Eurasia Finals 2025 will take place. The official opening of the championships will be on Monday, December 15. The detailed schedule is available on the [website](https://nerc.itmo.ru/regional/nef-2025.html). On our accounts, we’ll be sharing updates about the participants and their results. As usual, we’ve put together a list of useful materials in a single post; it will be updated gradually so you can conveniently follow the progress of the competitions and cheer for your favorites. By the wa...

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XIX Russia Team Open High School Programming Contest Hello friends! <img src="/predownloaded/35/ae/35aee9935721635f9e3ac44211a272a29f817147.jpg" align="right" style="height: 220px; margin: 10px 35px 20px;" alt="text"/> This weekend, on 8-9th of December &mdash; St. Petersburg, Barnaul, Kremenchug, Tbilisi, Almaty and Sochi will host the XIX Russia Team Open High School Programming Contest. Competition will be attended by more than 250 teams. Contest is held for the first time in Sochi this year -Educational Center “Sirius” will host nine teams. The main contest will start on **9th of December at 10:00**. You can follow current results by the [link](http://neerc.ifmo.ru/school/archive/2018-2019/ru-olymp-team-russia-2018-standings.html). Link to the tasks will be able right after the start of the tour. A [mirror](https://codeforces.me/contests/1090) will be available on [contest_time:1090] – this is for those, who are not a participant, but also want to solve interesting problems! Do not join our broadcasts if you plan to ta...

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Final Round Announcement: Path to Mastery (A&DS-1 and A&DS-2) Hello, Codeforces! We, [user:zeyd1234,2026-10-18] and [user:Arbuzik342,2026-10-18], are glad to present to you the final round of our contest! Participants will face two independent tracks: **A&DS-1** and **A&DS-2**. The winner of each track will receive prize from the Sirius Educational Center. ### Format and Structure Anyone within the rating limits can participate in the final. * Problems **D, E, F, G** in the A&DS-1 track and problems **A, B, C, D** in the A&DS-2 track are **shared**. * The rest of the problems in each track are unique. * The contest duration is **4 hours**. Each problem is divided into several subtasks and is scored in points. **Please note: the problems are NOT ordered by difficulty!** We recommend reading all problem statements before starting to solve. ### Schedule and Virtual Participation The contest starts at **18:00 MSK on October 18, 2026**. If you cannot participate in real-time, you can start a virtual contest within 72 hours after...

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# Qualification Round starts today at 17:35 MSK! # Qualification Round starts today at 17:35 MSK! Good day, dear Codeforces users! We would like to remind you that in less than 8 hours (at **17:35 Moscow time, UTC+3**), the Qualification Stage of our contest series based on Sirius Educational Centre problems will begin! Detailed rules, the scoring system, and track distribution criteria can be found in our [main announcement](https://codeforces.com). --- ### Key Details of the Qualification Round: * **Format:** You will be given **7 problems**. * **Duration:** Exactly **3 hours** (until 20:35 MSK). * **Registration Link:** [Register for the Qualification Stage](https://codeforces.com) --- ### Important Rating Restrictions for Prizes: * **Absolute Maximum:** Users with a maximum rating **above 1900** are not eligible for prizes at all. * **Advanced Track (DSA-Advanced):** **ALL** participants with a maximum rating of **1900 or lower** can compete for prizes (provided they successfully pass the qualificati...

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Why So Sirius?? Hey [user:heysem,2020-05-17], I see you are very anxious about catching me. Why is this much effort? What happened if I cheated one question?? Does that burned you? Or are you angry that you couldn't enter the contest? Don't make it this much big deal man.

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