Interactive problems are still a new topic which confuses many participants. Recently I failed to solve some of the interactive problems during contests, so I decided to practice this kind of question. For this purpose, I put together a mashup with 12 problems per 5 hours, with difficulties from Div 2 B to Div 1 C. You can upsolve the problems at your own pace.

**UPD:** video editorial live in 15 minutes: