def caesar_cipher_decryptor(key: int, encrypted_message: str) -> str:
    """Decrypts a message which has been encrypted using a Caesar Cipher.

    Args:
        encrypted_message (str): Message to be decrypted.
        key (int): Original shift.

    Returns:
        decrypted_message (str): Decrypted message.
    """
    decrypted_message = "".join([chr(((ord(char) - ord("a") - key) % 26) + ord("a")) for char in encrypted_message])

    return decrypted_message