#lang racket

(let-values ([(_ x y)
  (with-input-from-file "../input/02"
    (lambda ()
      (for/fold ([aim 0]
                 [x 0]
                 [y 0])
                ([line (in-lines)])
        (let ([s (string-split line)])
        (let ([op (car s)]
              [num (string->number (car (cdr s)))])
          (match op
            ["up" (values (- aim num) x y)]
            ["down" (values (+ aim num) x y)]
            ["forward" (values aim (+ x num) (+ y (* aim num)))]))))))
]) (values (cons x y) (* x y)))