(define (count-increase text-port previous count)
  (let [(line (get-line text-port))]
    (if (eof-object? line)
      count
      (let [(number (string->number line))]
	(count-increase text-port number 
			(+ count (if (> number previous) 1 0)))))))

(let [(file (open-input-file "input"))]
  (display "part 1: ")
  (display (count-increase file 100000 0))
  (newline)
  (close-port file))

(define (count-increase-sliding text-port triplet previous-sum count)
  (let [(line (get-line text-port))]
    (if (eof-object? line)
      count
      (let* [(number (string->number line))
	     (triplet (list (cadr triplet) (caddr triplet) number))
	     (sum (+ (car triplet) (cadr triplet) (caddr triplet)))]
	(count-increase-sliding text-port triplet sum
				(+ count (if (> sum previous-sum) 1 0)))))))

(define (read-number text-port)
  (string->number (get-line text-port)))

(let* [(file (open-input-file "input"))
       (triplet (list (read-number file) (read-number file) (read-number file)))
       (sum (+ (car triplet) (cadr triplet) (caddr triplet)))]
  (display "part 2: ")
  (display (count-increase-sliding file triplet sum 0))
  (newline)
  (close-port file))