# The Caesar Cipher Algorithm

def main():
    message = input("Enter message: ")
    key = int(input("Key [1-26]: "))
    mode = input("Encrypt or Decrypt [e/d]: ")

    if mode.lower().startswith('e'):
        mode = "encrypt"
    elif mode.lower().startswith('d'):
        mode = "decrypt"

    LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

    translated = ""

    message = message.upper()

    for symbol in message:
        if symbol in LETTERS:
            num = LETTERS.find(symbol)
            if mode == "encrypt":
                num = num + key
            elif mode == "decrypt":
                num = num - key

            if num >= len(LETTERS):
                num = num - len(LETTERS)
            elif num < 0:
                num = num + len(LETTERS)

            translated = translated + LETTERS[num]
        else:
            translated = translated + symbol

    if mode == "encrypt":
        print("Encryption:", translated)
    elif mode == "decrypt":
        print("Decryption:", translated)


if __name__ == '__main__':
    main()