import Control.Applicative
import Text.Printf

main = do
  xs <- fmap (read :: String -> Int) . words <$> getLine
  printf "%d\n" $ solve xs
  where
    solve (a:b:s:_)
      | s == 1 = abs (a - 1) + 1
      | otherwise = if abs (s-a) <= abs (s-b) then abs (s-a) + s
                      else abs (s-b) + abs (a-b) + a