(use srfi-19)

(define (main args)
  (let* [(n (read))
         (c4 (quotient (- n 2014) 400))
         (rsy (+ 2015 (* 400 c4)))
         (d4 (days-wednesday 2015 2414))]
    (print (+ (* c4 d4) (days-wednesday rsy n))))
  0)

(define (days-wednesday sy ey)
  (length
   (filter (^y (= y 3))
           (map (^y (date-week-day (make-date 0 0 0 0 23 7 y 0)))
                (iota (- ey sy -1) sy)))))