{-# LANGUAGE OverloadedStrings #-}
import           Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as B
import           Data.Char             (isUpper)
import           Data.Word             (Word8)

main :: IO ()
main = do
  a <- B.head <$> B.getLine
  if isUpper a
    then B.putStrLn "A"
    else B.putStrLn "a"
