{-# LANGUAGE OverloadedStrings #-}
import qualified Data.Attoparsec.ByteString.Char8 hiding (take)
import qualified Data.ByteString.Char8 as B

main :: IO ()
main = do
  (Done _ n) <- parse decimal <$> B.getLine
  B.putStr $ B.unpack $ show $ solve n

solve :: Int -> Int
solve n =
  | odd n = n * 2
  | even n = n


  
