(import (chicken io)
        (chicken string))

(define (part-1 port)
  (let loop ((h 0) (d 0))
    (let ((l (read-line port)))
      (if (eof-object? l)
        (* h d)
        (let* ((parts (string-split l))
               (act (car parts))
               (mag (string->number (cadr parts))))
          (cond ((equal? act "down")
                 (loop h (+ d mag)))
                ((equal? act "up")
                 (loop h (- d mag)))
                ((equal? act "forward")
                 (loop (+ h mag) d))
                (else (error "Bad action " act))))))))

(define (part-2 port)
  (let loop ((h 0) (d 0) (a 0))
    (let ((l (read-line port)))
      (if (eof-object? l)
        (* h d)
        (let* ((parts (string-split l))
               (act (car parts))
               (mag (string->number (cadr parts))))
          (cond ((equal? act "down")
                 (loop h d (+ a mag)))
                ((equal? act "up")
                 (loop h d (- a mag)))
                ((equal? act "forward")
                 (loop (+ h mag) (+ d (* a mag)) a))
                (else (error "Bad action " act))))))))


(call-with-input-file "input"
                      (lambda (p) (print (part-1 p))))

(call-with-input-file "input"
                      (lambda (p) (print (part-2 p))))