import Control.Applicative

main = do
    input <- fmap(read :: String -> Int) <$> words <$> getLine
    print $ f input

f (a:b:s:_)
    | s == 1 = abs (a - 1) + 1
    | abs (a - s) <= abs (b - s) = abs (a - s) + s
    | a == 0 = g a b s
    | otherwise = min (g a b s) (abs (b - s) + abs (a - s) + a)

g a b s = abs (b - s) + abs (a - 1) + s