(import (chicken string))
(import (chicken format))
(import (chicken io))
(import (chicken sort))
(import srfi-141)

(define numbers (map string->number (string-split (read-line) ",")))

; PART 1
(define sorted (sort numbers <))
(define median (list-ref sorted (floor/ (length numbers) 2)))

(define (part1)
  (foldl
   (lambda (x y) (+ x (abs (- y median))))
   0
   numbers))


; PART 2
(define (triangular n) (/ (* n (+ n 1)) 2))

(define (part2- avg)
  (foldl
   (lambda (x y) (+ x (triangular (abs (- y avg)))))
   0
   numbers))

(define avgCeil (ceiling/ (foldl + 0 numbers) (length numbers)))
(define avgFloor (floor/ (foldl + 0 numbers) (length numbers)))

(define (part2)
  (min (part2- avgCeil) (part2- avgFloor)))


(format #t "part 1: ~A~%" (part1))
(format #t "part 2: ~A~%" (part2))