The contest is over. 13 people solved all problems — you guys are amazing!

The editorial will be available here.

Today's language is FALSE, stack-based esoteric programming language invented over 20 years ago.

The traditional A+B problem (integers A and B are separated with a space) can be solved like this.

To test your solutions, you can:

• download source code in C of the original interpreter here. Testing system uses this interpreter with -q option.
• use "Custom Invocation".
• use online interpreters (they differ from the reference interpreter a bit but make debugging much easier): 1, 2.

Useful links:

• language description by its author Wouter van Oortmerssen
• Progopedia article
• examples at Rosetta Code

Notes:

1. Language description contains instructions ø and ß. The reference interpreter uses O and B instead (both online interpreters support ø and ß).
2. End of file is encoded as #-1, end of line — as #13#10.
3. The stack MUST be empty when program completes, otherwise the interpreter will post an error to stdout, and output will be judged as incorrect.

Surprise Language Round #7 will take place on September 13th, the Programmers' Day.

The rules of the contest are as follows:

• The contest is unrated for everybody.
• The round uses ACM ICPC rules: the standing is defined by the number of solved problems, ties are resolved based on penalty time. Initially the penalty is 0, and for each solved problem it is increased by submission time (since the start of the contest) + 20 minutes for each failed submission. The solution is considered to be correct if it passes all tests from a predefined test set; you know whether the solution is right immediately after sending it. There are no hacks.
• The round has 8 problems, sorted by estimated complexity, and you have 2 hours to solve it.
• Solutions are accepted only in one language, which will be announced at the beginning of the contest. The language was created a while ago, we didn't invent it for this occasion.
• Please reread this post at the beginning of the contest: we will announce the language and add instructions to install the compiler (the contest interface will provide an option to run your solutions online as well) and links to useful manuals. Other than that, learning the language is up to the competitor. You can use any resources to solve the problems (as long as you remember that this is an individual competition); you don't have to limit yourself to the manuals provided in the post.

I hope that the language I chose will be unknown to most of the competitors.

Hi Codeforces!

We would like to invite you to participate in Codeforces Round #266 Div2, which will be held this Friday, September 12th at 19:30 MSK. As usual, Div1 participants can take part out of the competition.

Problems have been prepared by Antoniuk and me. It's the second round prepared by us, and we still hope it won't be the last.

We want to thank Gerald for helping to prepare this round, Delinur for translating the statements, and also MikeMirzayanov for Codeforces and Polygon.

It will be used a standart scoring: 500-1000-1500-2000-2500.

Gl & hf!

UPD. Round has finished. Thanks for participating.
UPD2 Congratulations to top-5 participants:

1) dominator_hza
2) Final_Battle
3) free_pascal
4) vanhanh.pham
5) NUOUN

UPD3. Editorial .

Welcome to 2014-2015 CT S02E01: Codeforces Trainings Season 2 Episode 1 (NEERC 99 + misc). The training duration is 4.30 hours. It is opened for teams as well as for individual participants. After the end you may use the practice mode to complete problem solving. Also it will be availible as a virtual contest for whose of you who can't take part today. Please, do not cheat. Only fair play!

It is possible that the problems will be too easy for some participants, it is possible that we will add some problems.

Good luck!

The new season of a collegiate team championship ACM-ICPC is about to start. For example, the registration for the Southern (Saratov) Subregional Contest is already running. I am sure that many participants of the Codeforces rounds will take part in ACM-ICPC this year.

We are launching a series of weekly practice trainings on Codeforces. Naturally, they will be held within Codeforces::Gym. Feel free to participate!

The practice starts on Thursdays at about 12:10 PM (UTC), which is 16:10 Moscow Time. Expected duration is 4-5 hours. We are going to practice using the problems of different contests of the past years. All you need is common sense and observing these simple rules:

• We will not publish the problem source before the practice starts. We want you to solve the problems on your own in a fair competition. If you use somebody else’s code or cheat in any other way, you will be disqualified. If you don’t want to solve on your own, that’s fine, you don’t have to. But spoiling the practice for others is unacceptable.
• Do not discuss the problems till the practice ends.
• We will rarely answer the questions about problems. If you’ve found some obvious bug, please let me know. We will fix the bug and send everybody the note about the fix.
• If you have a coach account (and you do not participate in the practice), we will be grateful for your help.
• Please register for the practice with the people from your team who actually participates in it.
• From time to time, I am going to ask some of the jury of the past contests or coaches from other higher educational institutions to help with preparing or share materials — your understanding and help will be greatly appreciated!
• if you solved the contest problems before just switch to another training or inform us via problem questions form, we will move you to out-of-competition role.

The first contest 2014-2015 CT S02E01: Codeforces Trainings Season 2 Episode 1 (NEERC 99 + misc) takes place on September, 11, at about 12:10 PM (UTC).

Hi all.

On Sunday, September 7, at 19:30 MSK regular, 265-th, Codeforces round will take place. Problems are prepared by me, Mikhail Tikhomirov. Round will be for both divisions.

Standard (not dynamic) scoring will be used for this round.

Div. 1: 500-1500-1500-2000-2500

Div. 2: 500-1000-1500-2500-2500

I would like to thank Gerald Agapov (Gerald) for his help in problems preparation, Filipp Rukhovich (DPR-pavlin) and Alexander Mashrabov (map) for round testing, Maria Belova (Delinur) for English statements and Mikhail Mirzayanov (MikeMirzayanov) for creation and development of Codeforces project.

This is going to be my third round on Codeforces, and I tried to make problems as interesting and diverse as possible. Hope you will enjoy this round. Best of luck! =)

UPD: round is over. Thanks for participating, hope you liked the problems.

Grats to all the winners:

Div. 1:

1. tourist
2. Petr
3. rng_58
4. al13n
5. ecnerwala
6. qwerty787788
7. marek.cygan
8. KADR
9. Merkurev
10. hos.lyric

Special respect goes to simonlindholm, the only participant to solve the hardest problem E!

Div. 2:

1. matthew99
2. acrrca
3. ccdream
4. Chameleon2460
5. newSolars

Editorial is here.

Hello everyone,

I'd like to invite you to participate in a 2-hours Div2 round which will be held this Saturday, August 30th at 11:30 AM MSK. Div1 coders can take part out of competition, as usual. The problems were prepared by me and Archazey (B and C). I'd like to thank Gerald for helping preparation, Archazey for english translation and MikeMirzayanov for the Codeforces system.

The main characters of this round will be Caisa and Gargari,which have some interesting tasks for you. I hope you will enjoy the round. Good luck and have fun!

UPD: It will be used a standard scoring.

Here are the winners:

1.lymmd

2.for_the_pride

3.danilka.pro

4.zld3794954

5.nxihkke

Stats about hacks can be found here.

Editorial is here.

You enjoyed Bayan Programming Contest 2012-2013? Now we are happy to unveil Bayan Programming Contest 2014-2015! This will be Bayan's 3rd public programming contest and we have made several improvements and did our best to make the whole tournament even more fun! To register visit contest.bayan.ir right now!

Introducing the rounds

We are going to host 5 rounds:

1. The first round is named Shortcut!. Shortcut! round is mainly meant to help us actively test our new contest platform, but since we'd like to thank all the people participating in this round, the winner will bypass "all" intermediate rounds, and directly advance to the final onsite event! Top 5 contestants will also get a T-shirt. Shortcut! round is not going to be too hard and there is only 1 hour to solve 3 problems, making it harder to predict the round winner!

2. Warm-up is our second round and honoured to be hosted on Codeforces. Warm up is also not a required round but it is going to be rated for both divisions and the top 50 are going to win t-shirts.

3. Bayan Programming Contest officially begins with the Qualification round. It is going to be an easy event, and solving one problem is enough to advance to Elimination round. If you missed Shortcut! Round, make sure to get familiar with our new platform during this round. Also, 5 random participants will be receiving t-shirts.

4. Elimination round is the most challenging online round in this tournament. Top 100 participants will be receiving t-shirts, but only top 20 from 20 countries will get the chance to compete in the final (onsite) event.

5. Final round will be an onsite event. To find the onsite event's look and feel, you can watch this 4 minute video clip. More details will be announced later.

UPDATE:

Shortcut! Round Terms & Rules

• Shortcut! round will start at 13:00 UTC, 29 August 2014.
• Shortcut! round consists of three programming tasks and competitors will have just one hour to solve them.

Solving Problems

• Competitors may solve problems by any means and are free to use any programming language, library or computational application to solve problems. Given an input file, you should submit a correct output together with the source code used to produce that output within the specified time limit.
• Not submitting any file during the time limit, will be considered as an unsuccessful attempt.
• Both input and output formats are crucial. Adhere them precisely to avoid getting solutions judged as wrong.

Penalties

• Competitors may not use more than one user account.
• Competitors may not communicate with each other during the contest.
• Your output must be reproducible using the source code you provided.
• All submitted source codes will automatically get analyzed for code plagiarism detection.
• Cheaters will be banned forever from Bayan programming contests.

Judging

• Do not submit irrelevant clarifications during the contest.
• The decision of the judges are final in all matters.
• All source codes of the competitors will be published after each round.
• Bayan's staffs are not allowed to participate in the contest.

Score Calculation Method

• n = No. of accepted submissions
• t = Contestant's submission time
• T = Total contest duration
• p = Number of contestant's wrong attempts

Hello everyone!

snuke, EnumerativeCombinatorics and me would like to invite you to Codeforces Round #263 for both divisions. It will be held on Tuesday, August 26th at 18:00 MSK. Note that this round starts on different time from normal rounds.

Great thanks to Gerald for helping us prepare the round, MikeMirzayanov for creating a fine platform, and Delinur for translating the statements.

You'll help men named Appleman and Toastman in this round. Good luck and have fun!

UPD. In Div.1 and Div.2, scores will be standard, that is , 500-1000-1500-2000-2500 for each problem.

Now the contest is over! Thank you for participating!

Here are the winners:

Div1.

1. YuukaKazami

2. sankear

3. dreamoon_love_AA

4. Egor

5. Memset137

Div2.

1. yyt16384

2. SuzuKuma2112

3. pawky

4. AlexandruValeanu

5. mosiomohsen

Congratulations on YuukaKazami, who solved all the problems !

Editorial is here

Hello, CodeForces! On 20 August at 19:30 MSK will take place 262 (Div. 2) round. Div1 — participants can take part out of competition, as usual.

The problems were prepared by Victor Vasilevsky(vitux) and Aliaksei Semchankau (me). We'd like to thank Gerald Agapov (Gerald) for help of preparation of this round, Michael Mirzayanov (MikeMirzayanov) for comfortable platformes Codeforces and Polygon, and Mary Belova (Delinur) for translation of statements.

In this round you will help to different good people. We sure that every participant will find an interesting problem for him:)

gl & hf!

UPD: It will be used a standard scoring.

UPD2: Also we'd like to thank Vitaly Aksenov(Aksenov239) who helped a lot in fixing of Russian statements.

UPD3: We'd like to congrat top-5 participants!:

1) buptcjj

2) 6wr1

3) ladpro98

4) shaojj

5) linjek

Also we'd like to congrat jellygendut, who got 20th place and solved problem Е — It has been solved by 3 participants. Nobody has solved all problems, but every problems were solved by participants succesfully.