(let ((mday '(31 28 31 30 31 30 31 31 30 31 30 31 0)))
  (let loop ((m 1) (d 1) (lastday (car mday)) (lastdays (cdr mday)) (c 0))
    (cond ((zero? lastday) (print c))
          ((> d lastday) (loop (+ m 1) 1 (car lastdays) (cdr lastdays) c))
          ((= m (+ (div d 10) (mod d 10)))
           (loop m (+ d 1) lastday lastdays (+ c 1)))
          (else (loop m (+ d 1) lastday lastdays c)))))