Welcome to the Codeforces Beta Round #6.
It will be good to see your feedback and impressions in the comments.
Wish you high rating,
UPD. It seems the problem D has some tricky issues around judge solutions. Judge solutions will be fixed and the problem will be rejudged. If it will affect many participants, the contest will not be rated.
UPD 2. We have reduced constraints in the problem D and made rejudge. No solution passed tests. So the rejudge affected significantly only 4 participants, who solved it during the contest. But all of them increase their rating if we will count the contest as rated event. So we decided to make it rated and put problem with lowered constraints into the practice.
UPD 3. And by the way, the round tutorial is waiting for a volunteer. The tutorial should be in Russian and in English. It will be published on the homepage and later will be available via special link from the contest page.