#!/usr/bin/env gosh

(define (order-times x y l)
  (+
   (if (zero? x) 0 1)
   (if (< y 0) 1 0)
   (ceiling (/ (abs x) l))
   (ceiling (/ (abs y) l))
   )

  )

(define (main _)
  (let* ([x (read)][y (read)][l (read)])
    (display (order-times x y l))
    )
  (newline)
  0)