(define eom '(31 28 31 30 31 30 31 31 30 31 30 31))
(define ds (iota 31 1))

(define (sum-digit x)
  (if (< x 10)
      x
      (+ (div x 10) (mod x 10))))

(define sdod (map (^ (x) (sum-digit x)) ds))

(let loop ([i 0] [s 0])
  (if (= i 12)
      (format #t "~d~%" s)
      (loop (+ i 1) (+ s(length (filter (^ (x) (= x (+ i 1))) sdod))))))