Hello, Codeforces!

We have planned this round as a Div. 4, but testing showed us, that problems are more suitable for Div. 3. Therefore, instead of the previously announced Div. 4 we will hold Div. 3 round.

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Hello! Codeforces Round #644 (Div. 3) will start at 24 мая 2020 г. в 16:35. You will be offered 6 or 7 problems (or 8) with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 or 7 (or 8) problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as trusted participants of the third division, you must:

• take part in at least two rated rounds (and solve at least one problem in each of them),
• do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

The problems for this round were invented MikeMirzayanov and prepared by me and Stepavly

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to antontrygubO_o iankury bfs.07 kocko Ilya-bar arsijo pashka Gassa neal for help in round preparation and testing the round.

Good luck!

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