This editorial corresponds to 2017 Chinese Multi-University Training, BeihangU Contest, whose replay contest will start on Jul/25/2017 07:00 (Moscow time).

There are ?? problems in total. You can solve them as a team member or an individual in a 5-hour contest. By the time you join as virtual participants, 770 teams, or even more, will compete with you virtually.

Editorial in the English version has been completed, which is a bit different from its Chinese version (mostly because I don't want bad editorials to ruin the contest, lol). However, for the sake of hiding spoilers, solutions are locked and will be shown as the following conditions are met:

• Solutions for the easiest ? problems will be revealed after the replay;
• Each for the hardest ? will be released if the corresponding problem has been solved by at least ? users or teams;
• Each for the others will be published when the relevant problem has been solved by at least ?? users or teams in virtual participation.

Or you can find solutions in comments?

The above missing parts, denoted by question marks, will be replaced by real numbers soon after the replay. Now they are hidden to prevent from telling you the difficulty distribution of problems.

This is just a small attempt in order to attract more participation. Hope you can enjoy it.

Any comments, as well as downvotes, would be appreciated.