main = do
 [x,y,l] <- map read . words <$> getContents
 print (robot x y l)

robot x y l = (div' x l) + (div' y l) + (rotate x y)
 where
  div' a b = let (d,m) = divMod (abs a) (abs b) in d + signum m
  rotate x y
   | x==0 && y>=0 = 0
   | y>=0 = 1
   | otherwise = 2