(define x (read))
(define y (read))
(define l (read))

(define turn
  (lambda (x y)
    (cond ((and (zero? x) (>= y 0)) 0)
          ((and (>= y 0)) 1)
          (else 2))))

(print (let loop ((X (abs x)) (Y (abs y)) (L l) (cnt (turn x y)))
         (cond ((> X 0)
                (loop (- X L) Y L (+ cnt 1)))
               ((> Y 0)
                (loop X (- Y L) L (+ cnt 1)))
               (else cnt))))