import Data.Char (isUpper)
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as BSC8

readString :: ByteString -> [String]
readString = map BSC8.unpack . BSC8.words

getString :: IO [String]
getString = readString <$> BSC8.getLine

main :: IO ()
main = do
  [s] <- getString
  if isUpper =<< s
    then putStrLn "A"
    else putStrLn "a"