import Data.Char (ord, chr, isUpper, isAlpha)
 
encrypt :: Int -> String -> String
encrypt = (<$>) . shift
 
decrypt :: Int -> String -> String
decrypt = encrypt . negate
 
shift :: Int -> Char -> Char
shift key char
  |isAlpha char = chr $ intAlpha + mod ((ord char - intAlpha) + key) 26
  |otherwise = char
  where
    intAlpha =
      ord
        (if isUpper char
           then 'A'
           else 'a')
 
solve :: String -> Int -> Int -> IO ()
solve str loop numLoops = do
    let encode = encrypt (loop) str
    let out = "Caesar " ++ show loop ++ ": " ++ encode
    putStrLn out
    let c = loop + 1
    if loop /= numLoops
    then solve str c numLoops
    else putStrLn ""
 
main :: IO ()
main = do
    let message = "I love Haskell"
    let key = 10
    let originalMessage = "Original: " ++ message
    putStrLn originalMessage
    let encrypted = encrypt key message
    let encryptedMessage = "Encrypted: " ++ encrypted
    putStrLn encryptedMessage
    let decrypted = decrypt key encrypted
    let decryptedMessage = "Decrypted: " ++ decrypted
    putStrLn decryptedMessage
    solve message 0 26

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