import Prelude

main :: IO ()
main = do
  [x, y, l] <- map read . lines <$> getContents
  print $ calc x y l

calc :: Int -> Int -> Int -> Int
calc x y l = turns x y + over (abs x) l + over (abs y) l

turns :: Int -> Int -> Int
turns x y | x == 0 && y >= 0 = 0
          | y >= 0           = 1
          | otherwise        = 2

over :: Int -> Int -> Int
over x l = div x l + if mod x l == 0 then 0 else 1