THE VAGUE PROBLEM  (L9)

Riverside Community Garden is run by volunteers. All names and details
below are invented. This is the message the committee chair sent you:

----------------------------------------------------------------------
"Hi! Could you sort out a fair watering rota for the summer? The beds
dry out fast and last year it was chaos. Here's who has said they can
help. Thanks so much!

  Ana   - weekdays after 5 pm, but never Wednesdays
  Ben   - weekends only
  Chloe - any day, mornings only
  Dev   - Mondays, Tuesdays and Thursdays, any time;
          away for two weeks in the middle of July
  Eli   - Saturdays
  Fran  - any day, but no more than once a week (bad back)"
----------------------------------------------------------------------

Things you may want to know, if you think to ask (the chair would
answer these if asked; a stranger reading your spec cannot ask):
  - The rota should run for 13 weeks. Week 1 starts on a Monday in
    early June. Dev is away for all of weeks 7 and 8.
  - The beds need watering once a day, every day, either in the
    morning (before 10 am) or in the evening (after 5 pm). One person
    is enough for one watering.
  - The committee will print the rota on one page and pin it to the
    shed door.
  - "Fair" was not defined by the committee. That is your decision to
    make and to state.
