VERY IMPORTANT NOTE TO ALL DEC COURSE 2022 PARTICIPANTS (due to delays in email communication): Elementary is gone, so Advanced has a diagnostic test (if you fail, no Dec Course). Syllabus of diagnostic is anything in these prerequisite notes, please review them at this link. Problemsets can be found at this link and under Contests (Collections).
Each side of the field is a permutation of integers from 1 to N.
Note that you can apply cyclic shifts on any side of the road, but not both at the same time.