Hi everybody!

First, I invite you to take part in an official Testing Round 12. The fact is, the Codeforces team has made numerous changes to the platform (details are below), and we want to be sure that the basic functionality remained unchanged. This round will have a shortened duration of 1.5 hours, consist of 3 (maybe 4) problems that you might have already seen before. Its purpose is to test the system on the one hand, and on the other hand — to brighten up a Wednesday evening. Of course, the round will be unrated.

Now the main thing. This coming Friday (yes, the 13th of November) Codeforces starts another line of rounds. We called them Educational Rounds. Using my students at the Saratov State University Programmings Competitions Training Center as an example, I regularly notice that even those who have a considerable progress in the results on the rounds often have narrow purview in terms of standard topics and ideas, they are not familiar with many well-known problems and methods. The fact is, the rounds often avoid any folk or classical subjects, thus underdeveloping the purview of young generation of the participants.

We are pleased to announce the start of a series of educational rounds! They will take place with the regularity of a round 2-4 times per month.

Their characteristics are like that:

• The duration is classic — 1.5 — 2.5 hours;
• The goal is rather to practice and to educate, than to compete;
• Not only problems, but also exercises can be used;
• Useful, even well-known ideas will be reused in order to introduce them to a wide range of participants;
• Often the formal text of the statements;
• Unrated (perhaps for now);
• We will try to conduct them in the ACM-ICPC mode (if there are long waiting lists, we may change the approach);
• The results that are obtained after the end of the round, are preliminary;
• After the end of the round will be a 24-hour period of open hacks — any visitor of Codeforces may try to hack any complete solution to a problem of the last round (either from a contest, or from practice), the source code of hacking solution is available (you can copy the text and, for example, stress it);
• All successful hacks from the previous item will be added to the official test set and after as long as 24 hours after the end of the round retesting of all complete solutions will be made;
• Only after the final standings based on improved test data, the results are final;
• The results of a round are calculated separately by division;
• Our ability to process such problems are limited, so actually the test suites from the jury are expected to end up incomplete — we are looking forward to your hacks!

Basically, we will be oriented towards the members of the second division, but often these rounds will be of interest to more experienced participants.

For now preparing problems to these rounds will be concentrated at the Saratov State University Programming Competitions Training Center, most of the work with the problems will be accomplished by Edvard Edvard Davtyan. We wish him good luck, enthusiasm and energy!

See you at the Testing Round 12, and later at the Educational Codeforces Round 1.