import System.Environment (getArgs)
import qualified System.IO.Lazy.Input as LI
import qualified System.IO.Strict as SIO
import Data.Char
main = LI.run' . (fmap (SIO.putStr . fmap swapCase) . LI.concat . map LI.readFile) =<< getArgs
  where swapCase c | isUpper c = toLower c
                   | otherwise = toUpper c