Today at 19.30, Moscow time there will be Codeforces Round #319 and it's strongly disadvised to skip it.
I'm the author of this round, my name is Dima Gorbunov and it's my first round on Codeforces. I really hope you're going to like it and everyone will find a satisfying problem. In order to increase the probability of finding that task, please read all of the problem statements.
As usual, I'd like to thank Zlobober for his invaluable help and his special sense of humour, sankear for coding additional solutions, Delinur for the English statements and MikeMirzayanov for amazing systems Codeforces and Polygon.
You're going to have two hours to solve 5 problems. Good luck!
UPD. The scores in first division are 500-1250-1250-2000-2750.
In second division — 500-1250-1500-2250-2250,
UPD2. Because of large size tests for some of the problems, system testing will be slow (it's possible that it will take several hours). Thanks for your patience!
UPD3. English editorial is also accessible.
A special respect to al13n for correct solution of Div1.E during the contest!