import Control.Applicative

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

f (a:b:s:_)
    | s == 1 = abs (a - s) + s
    | otherwise = if abs (a - s) <= abs (b - s) then abs (a - s) + s else abs (b - s) + s - 1 + a