By HolkinPV, 12 years ago, translation, In English

Welcome, friends)

We are glad to introduce you regular Codeforces round #123 for Div.2 participants. Everyone can traditionally participate in it.

Problems are prepared by command of authors: Ivan Fefer (Fefer_Ivan), Igor Kudryashov (Igor_Kudryashov), Pavel Kholkin (HolkinPV) and Gerald Agapov (Gerald). Also thanks to Pavel Kunyavskiy (PavelKunyavskiy) and Alexander Kouprin (Alex_KPR) for their help. And traditionally thanks to Michael Mirzayanov (MikeMirzayanov) for Codeforces system and Mary Belova (Delinur) for translating problems.

Score distribution is standard: 500, 1000, 1500, 2000, 2500.

We wish you success and high rating!

Congratulations to winners:

  1. bmerry
  2. adrian.jaskolka
  3. cheshire_cat
  4. alexej
  5. psw

UPD: the tutorial is here

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By tunyash, 12 years ago, translation, In English

The upcoming contest is brought to you by me. My name is Arthur, I'm a student of Chelyabinsk lyceum 31.

I am glad to thank Gerald for contest preparation management, Delinur for translation of statements, MikeMirzayanov for a really excellent system, dolphinigle for test-solving, proof-reading and much valuable advice, fdoer, grey_wind, Skird and alger95 for help in problem development.

There is nothing more to say yet. As you can see, contest will be held in two divisions separately. The scoring system will be standard (not dynamic), but scores for tasks may be unusual (see update of this post).

There won't be volume stories. I hope you will like the contest and its problemset and everything will be OK.

UPD: Scores for tasks:

Division 1: 500-1000-2000-2000-2500

Division 2: 500-1000-1500-2000-3000


Congrats to winners =)


  1. Petr
  2. tourist
  3. yeputons
  4. peter50216
  5. aram90


  1. lucien
  2. tomasz.kociumaka
  3. sjynoi

UPD3 some part of English editoral posted. You will find the remaining part of the editorial later

UPD4 English editoral was completed.

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By MikeMirzayanov, 12 years ago, translation, In English

The first information letter

General information

In the first part of August 2012 Saratov State University runs an international student summer school in computer programming. The exact dates are 1-11 of August. Teams of three people and individual participants are invited to take part in it.

The school will take place in a picturesque place at one of Saratov resort centers on the Volga bank. The participants will be provided comfortable rooms for 2-4 people and meals three times a day. The resort center owns a beach and sport grounds.

It will be 10 training days. The school includes lectures by Saratov state university coaches, joint trainings, problems tutorials and topical workshops. The curriculum is designed for younger university students who aspire to achieve high results at programming competitions. Official language — Russian.

The fees are 16000 RUR (~ 510 USD) per a person. Moreover, each team or an individual participant should bring a laptop with the support of WI-FI.

All interested participants and teams should register at till 15th June 2012. Don't postpone the registration, as the number of participants we can take is limited.

You can get additional information by e-mail mirzayanovmr[symbol-at] As since the official language of the school is Russian, the registration requires knowledge of Russian. Also it is recommended to view this page in Russian.

About Saratov State University

Saratov State University, regularly achieves significant advances in programming competitions. The following are the main achievements of the university in international competitions:

  • 2002 ACM-ICPC World Finals silver medals, Europian Champions
  • 2003 ACM-ICPC World Finals silver medals
  • 2006 ACM-ICPC World Finals golden medals, Europian Champions, World Champions
  • 2007 ACM-ICPC World Finals silver medals
  • 2008 NEERC Champions
  • 2009 ACM-ICPC World Finals golden medals
  • 2010 ACM-ICPC World Finals silver medals
  • 2011 ACM-ICPC World Finals silver medals

Mike Mirzayanov,
Saratov State University

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By ifsmirnov, 12 years ago, translation, In English

Hello, dear Codeforces community!

I'm glad to present you the next Codeforces Round #121. The contest is brought to you by Ivan Smirnov (ifsmirnov) and Aleksandr Timin (AlTimin), the students of Moscow Institute of Physics and Technology. In our first round we will offer you a good time in Berland: you will hold a demonstration, prevent the demonstration, deal with the most important problems of Berland (with both of them!) and much more.

We thank Gerald a lot for the invaluable help he gave as during the contest preparation. He is also the author of one task in the contest. We also thank Delinur for the English version of statements, Aksenov239 for proofreading the statements and MikeMirzayanov for an opportunity to hold a contest on this wonderful site.

As usual, the contest will be held in both divisions and the problemsets will overlap. The scoring will be published later.

We wish you good luck and hope that you enjoy the contest!

UPD1: The scoring is classic in both divisions — 500-1000-1500-2000-2500.

UPD2: The contest authors apologize to the contesters for a possibility of misunderstanding of problem B div 1 (D div 2). The statement was fixed soon enough and the incorrect understanding of the problem didn't pass pretests, so the round is rated.

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By Nickolas, 12 years ago, translation, In English

The contest is over; the editorial is here. I've mis-estimated the complexity of the problems — but how could I possibly guess who will arrive and finish everything in 40 minutes :-) Congratulations to the winners — the slowest and the most relaxed of them took under an hour to solve all the problems.

Today's round features Roco — a little-known esoteric language with a special approach to loops and subroutines. The programs written in it look a bit bulky, especially when compared to Befunge, but this is compensated by their relative simplicity and readability. Here is a program which calculates the sum of two given numbers:

iin [0]
iin [1]
add [2] [1] [0]
iout [2]

There is little information about this language on the web — the only two sources known to me are the author's site and Progopedia article with commented sample programs.

There is also exactly one interpreter for Roco, written by its author. To run it, one has to have C++ installed (the author uses g++, and so do we), compile the interpreter source code into an executable file and run programs using command "roco program.roco". You can download the interpreter here.

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Announcement of Surprise Language Round 6
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By MaximShipko, 12 years ago, translation, In English


There are a lot of contests and trainings on Codeforces now. And it's difficult to find a tutorial or announcement for a specific contest.

And now you have an opportunity to attach materials (Codeforces blogs or external URLs) to any contest. You can click on the paperclip below blog's title and fill the popup form to attach blog entry to the contest. Or you can attach any URL in the contest's sidebar frame. There you can see resources that are already attached to the contest. Visibility of material depends on user's locale and current phase of the contest. For example you can't view statements before contest start.

The access to manage (add or delete) resources of the contest have administrators, contest managers and all "red" users.

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By Nerevar, 12 years ago, translation, In English

The contests starts at 12.00 MSK.

There are some links where you can get some information about the conduct of the contest.

Have fun watching the finals!

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By riadwaw, 12 years ago, translation, In English

Kostroma and I are problemsetters of Codeforces Round #120. It's first our contest and we hope you (and we too) will like it.

It's round for second division, but we think that everyone will find interesting problem for him.

Thanks for the help STAJIKER, HeroShadow, victor_kamashev, Abra, ifsmirnov, Aksenov239 and Gerald.
Thanks MikeMirzayanov for CodeForces platform and Delinur for English statements.

Good luck!

UPD: As usual, problems will cost 500-1000-1500-2000-2500 points.
UPD2: Problems are sorted according to expected difficulty.
UPD3: There was our mistake. The editorial was available for few minutes. If you see it, please not discuss problems and solutions. Now it is hided. In any case the round will be held. Decision, will contest rated or not will be made after contest. We are sorry for that.
UPD4: It's now known that only three participants from Div.2 have seen page with editorial while it was published (and 8 people in total). We'll not say any names, but we ask this people to not say anybody anything about the problem and to not use any post materials, if you have them. Thanks in advance.
UPD5: Please, don't panic. While your solution is in queue, you may solve other problems.
UPD6: Due to technical issues round is considered unrated. This problem and incident with editorial are strong enough reason for this decision. You may send your solutions to contest. They will be judged. We hope, that these technical problems will not spoil your impression about this round. Our sincere apologies. UPD7: Contest is over. Editorial is published. We hope, you like problems, prepared by us. We apologize again.
P.S: Excuse me, I don't know, when solution will be judged.

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By Nerevar, 12 years ago, translation, In English

On the second day of staying in the Polish capital we went for a walk in the city centre. It was cold, windy and a little rainy, so those of us who hadn't taken any warm clothes to Poland, had to buy hats, scarves and jumpers with Polish national symbols in souvenir shops. We were very impressed by the Old Town (Stare Miasto) that was destroyed in the World War II but then rebuilt. Actually, that's what comes to my mind when I imagine a historical centre of a European city: narrow sett-paved streats, clock towers with high spines, tiled roofs...

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By Nerevar, 12 years ago, translation, In English

This entry begins a small account of the journey Saratov State University delegation has left for the World Finals of the ACM ICPC 2012. The destination is Warsaw, where the World Finals take place this year. The delegation members are:

  • Maxim Ivanov (e-maxx), Artem Rakhov (RAD), Nickolay Kuznetsov (NALP) — the Saratov SU 2 team;
  • Michail Mirzayanov, the coach, with his wife Katherine and his daughter Tanya;
  • Antonina Fedorova and Tatiana Semenova, our administrators;
  • and finally, me (Nerevar), as the second coach.

That is the team’s second and last journey to the finals (last year they brought silver medals from Orlando). And for me this is the first journey to the Finals not as a participant (I participated in 2009 and 2010, and was a success too).

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