# Project 2: ROT13 Cipher

# define the alphabet as one long string
alphabet = "abcdefghijklmnopqrstuvwxyz"

# get user input, store it as a string
secret_code = input("Please enter the secret text.\n")
# convert to lower case
secret_code.lower()
print(f"Original text: {secret_code}")

#initialize empty output string
output = ""
#for each character in user input
for char in secret_code:
    # get the position of each letter in the alphabet
    index = alphabet.find(char)
    # if position not found
    if index == -1:
        # don't translate, write directly to output
        output += char
    # otherwise
    else:
        # shift the character by 13, according to alphabet string
        index += 13
        # deal appropriately with remainder. If using modulo, this
        # will do nothing if index is already less than 26
        index = index % 26
        # write the output
        output += alphabet[index]


# print new string (the encrypted message)
# It should work in reverse!
print(output)