module Main where

import Data.Bool

main :: IO ()
main = do
  { x <- getInt
  ; y <- getInt
  ; l <- getInt
  ; print $ rcount (x,y) + dist l (x,y)
  }

rcount :: (Int,Int) -> Int
rcount (x,y) = case (signum x,signum y) of
  (1,1) -> 1
  (1,0) -> 1
  (1,-1) -> 2
  (0,1) -> 0
  (0,0) -> 0
  (0,-1) -> 2
  (-1,1) -> 1
  (-1,0) -> 1
  (-1,-1) -> 2

dist :: Int -> (Int,Int) -> Int
dist z (x,y) = case divMod (abs x) z of
  (d,m) -> case divMod (abs y) z of
    (d',m') -> bool (succ d) d (m == 0) + bool (succ d') d' (m' == 0)

getInt :: IO Int
getInt = read <$> getLine