main = do
  x <- readLn
  y <- readLn
  l <- readLn
  print $ compute x y l

compute :: Int -> Int -> Int -> Int
{-
compute x y l = inner (compare y 0) (compare x 0) where
  inner GT EQ = yl
  inner GT _  = yl + 1 + xl
  inner LT EQ = 2 + yl
  inner LT _  = 1 + xl + 1 + yl
  inner EQ EQ = 0
  inner EQ _  = 1 + xl
  
  xl = steps x l
  yl = steps y l
-}
compute x y l =
  if y < 0 then xl + yl + 2 else
    if x == 0 then yl else xl + yl + 1
 where
  xl = steps x l
  yl = steps y l

steps x l = let (p,q) = divMod (abs x) l in if q == 0 then p else p+1