main :: IO ()
main = do
  x <- readLn
  y <- readLn
  l <- readLn
  print $ solver x y l
solver :: Int -> Int -> Int -> Int
solver x y l
  | x == 0 && y == 0 = 0
  | x /= 0 && y > 0  = 1 + (mc (abs x) l) + (mc y l)
  | x == 0 && y > 0  = mc y l
  | x /= 0 && y < 0  = 2 + (mc (abs x) l) + (mc (abs y) l)
  | x == 0 && y < 0  = 2 + (mc (abs y) l)
  | otherwise        = 1 + (mc (abs x) l)
  where mc a b = (a + b - 1) `div` b