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**.

<almost-copy-pasted-part>

Hello! Codeforces Round #644 (Div. 3) will start at May/24/2020 16:35 (Moscow time). You will be offered 8 problems 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 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 by 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!

</almost-copy-pasted-part>