import Control.Monad

main = do
    [x, y, l] <- replicateM 3 readLn
    let ans =
            sum
                [ (abs x + l - 1) `div` l
                , (abs y + l - 1) `div` l
                , if y < 0
                  then 2
                  else if x /= 0
                  then 1
                  else 0
                ]
    print ans