**UPD:**

# | User | Rating |
---|---|---|

1 | MiFaFaOvO | 3520 |

2 | tourist | 3461 |

3 | Um_nik | 3367 |

4 | apiadu | 3351 |

5 | mnbvmar | 3332 |

6 | Benq | 3330 |

7 | LHiC | 3276 |

8 | TLE | 3271 |

9 | Radewoosh | 3251 |

10 | ecnerwala | 3241 |

# | User | Contrib. |
---|---|---|

1 | antontrygubO_o | 189 |

2 | Errichto | 188 |

3 | tourist | 180 |

4 | Radewoosh | 173 |

5 | pikmike | 165 |

5 | vovuh | 165 |

7 | ko_osaga | 162 |

8 | Um_nik | 161 |

9 | rng_58 | 155 |

10 | farmersrice | 153 |

Hi everybody

Today the author of the majority of problems is Dmitry Zhukov, many thanks to him for this.

Also I want to thank Mike Mirzayanov for choosing problems for the contest and organizing it and Julia Satushina for the translation of the statements.

Good luck!

Announcement of Codeforces Beta Round #23

__Sorting__

In this problem one should find a minimal element from all elements, that are strictly greater, then the minimal one or report that it doesn't exist. Of course, there can be a lot of different solutions, but one of the simplest - to sort the given sequence and print the first element, that's not equal to the previous. If all elements are equal, then the required element doesn't exist.

Tutorial of Codeforces Beta Round #22 (Div. 2 Only)

Welcome all to Codeforces Beta Round #22

Note that at this time registration is possible during the round. The contest will begin at 19:00 MSK.

Today I am an author of the problems. I would like to thank Mike Mirzayanov for help in contest preparations, Edvard Davtyan and Nickolay Kuznetsov for writing the verification solutions, and Julia Satushina for translating statements into English.

Good luck on the contest!

**UPD**: The contest is over. Thank you all for participating!

Problems

Results

Winner Kasparyanm_Mihail gains +203 to rating after the contest!

Announcement of Codeforces Beta Round #22 (Div. 2 Only)

I invite you to participate:) Round will be non-rated, but there will not be limited registration at this time! **Please, read ****the rules**** before the contest!**

Announcement of Codeforces Alpha Round #21 (Codeforces format)

Authors of today's contest are Artem Rakhov and me. Thanks to Mike Mirzayanov, Edvard Davtyan and Julia Satushina for help in the organisation.

I hope, you will have fun.

Good luck!

**P.S.** After start of the contest, you can download the statements:

**UPD**. The contest has finished and you can see the standings and tasks. The winner and only participant who has solved all the problems is kalinov. Congratulations!

Announcement of Codeforces Beta Round #19

*You may read complete rules here.*

The text contains only preliminary rules of Codeforces contests — something surely will change. In particular, I hope to help the community to find the illogic in the rules. However, I have already discussed the format with programming contests dinosaurs and made unrated alpha contests — it seems rules are OK.

I think than the format 5 tasks x 2 hour is quite good. For this reason, in the near future we will not change it, but of course, experiments are possible.

** 1.** Before the competition all participants are divided into rooms, each room contains about 20 participants. For now random strategy works, but after a while it will be somehow correlated with the rating.

Two features were added to the interface in order to improve the view of the contest standings.

__Pythagorean theorem, brute force__

In this problem you should implement a function, which takes three points and checks whether they form a right-angled triangle. There are a lot of ways to do so, but the simplest one is using a Pythagorean theorem.

Tutorial of Codeforces Beta Round #18 (Div. 2 Only)

Welcome to Codeforces Beta Round #18

Authors of today's contest are Mike Mirzayanov, Edvard Davtyan and me. Thanks to Dmitry Matov for his help in statements preparation and Julia Satushina for translation of problems in English.

Good luck everyone!

- Problems
- Final standings
- Contest winner: I_am_Feeling_Lucky

Announcement of Codeforces Beta Round #18 (Div. 2 Only)

Contest discussion

Problem A. Noldbach problem

To solve this problem you were to find prime numbers in range [2..*N*]. The constraints were pretty small, so you could do that in any way - using the Sieve of Eratosthenes or simply looping over all possible divisors of a number.

Take every pair of neighboring prime numbers and check if their sum increased by 1 is a prime number too. Count the number of these pairs, compare it to*K* and output the result.

**Problem B. Hierarchy**

Problem A. Noldbach problem

Take every pair of neighboring prime numbers and check if their sum increased by 1 is a prime number too. Count the number of these pairs, compare it to

Tutorial of Codeforces Beta Round #17

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