How to Use:

Run the program: Execute the script in a Python environment.

Choose the operation: You will be prompted to choose whether you want to encrypt or decrypt a message by typing 'E' or 'D'.

Input the message: Enter the message you want to encrypt or decrypt.

Input the shift value: Enter the shift value (an integer) to use for the Caesar cipher.

View the result: The program will display the encrypted or decrypted message.

Repeat or exit: You can choose to process another message or exit the program.