(use srfi-1)
(use srfi-19)
(use srfi-42)

(let ((ds (filter (compose (cut = <> 5) date-week-day)
                  (drop (list-ec (: y 2008 2014) (: m 1 13)
                                 (make-date 0 0 0 0 13 m y 0))
                        7))))
  (for-each (compose print (cut date->string <> "~1")) ds)
  (print (length ds)))