import Control.Applicative ((<$>), (<*>))

main :: IO ()
main = solve <$> (map read <$> words <$> getLine) <*> (map read <$> words <$> getLine) >>= print

solve :: [Int] -> [Int] -> Int
solve [x, y] [x2, y2] | (abs x) == (abs y) &&
                        (abs x2) == (abs y2) &&
                        x * x2 + y * y2 > 0 &&
                        (abs x) > (abs x2) = (abs x) + 1
                      | otherwise = max (abs x) (abs y)