As usual, we meet at 4pm in MSC E306.

PLAN: like last time, I prepared five "surprise" problems of moderate
difficulty, selected from the A sessions of various Putnam exams.
Our plan was to work on them as a group.

FILES:
  a-surprise-1.pdf --- first page, just the problems, readable right away
  a-surprise.pdf   --- problems and solutions

POSTSCRIPT: only Matthew (plus Sasha) attended, and we only looked at
the "2018 A-3" problem (see file 2018-A-3.png). To allow us to recycle
the other problems, I decided to leave the PDF files unreadable.