Problem of the day? I've been working on understanding the solution (http://www.usaco.org/current/data/sol_cowdate_platinum_feb19.html) to a large question (http://www.usaco.org/index.php?page=viewproblem2&cpid=924) for the last hour or so, and I'm completely stuck at this point.

Might be fun for someone else to try out.

Question:
http://mathb.in/31958