# CSE 142 Python sessions
# This program creates a secret message using a simple encryption algorithm
# called a Caesar cipher, which shifts each letter ahead by 3 places.
#
# Sample log of execution:
# Enter your message: Attack the zombies at dawn!
# The encoded message is: dwwdfn wkh crpelhv dw gdzq!


def code(message, shift):
    message = message.lower()
    codedMessage = ""
    for x in message:
        if x in "abcdefghijklmnopqrstuvwxyz":
            num = ord(x)
            num += shift
            if num > ord("z"):     # wrap if necessary
                num -= 26
            codedMessage = codedMessage + chr(num)
        else:
            codedMessage = codedMessage + x
    return codedMessage


# main program
shift = 3
msg = input("Enter your message: ")
codedMessage = code(msg,shift)
print("The encoded message is:", codedMessage)