Hello Codeforces!

I will hold a Q&A/AMA stream on Twitch on Tuesday, 21 MSK (UTC+3).
You can write your questions in chat during the stream, or send them in this form beforehand (for example, if you can't attend the stream in person). Recording will be uploaded on YouTube afterwards.
Questions written in Russian will be answered in Russian, questions written in English — in English, questions written in other languages won't be answered because I can't understand them. I won't answer a question if I don't want to. Hopefully, the multilingual nature of the stream will be resolved afterwards by interested people who will add subtitles.
Questions can be about anything, but once again, I won't answer a question if I don't want to.

Huge thanks to lperovskaya who has agreed to help with this.

UPD: I won't answer questions like "how to become red", "how to become better at topic X", "how to win icpc wf". Answer