Answer: Secret Code #78

The secret message says:

PELICAN

The shift was 2.

Letter by letter

Secret letter	C	E	G	K	N	P	R
Real letter	A	C	E	I	L	N	P

Decode it with Python

This program does the decoding for you. Change the secret and the shift to crack other messages!

secret = "RGNKECP"
shift = 2
message = ""

for letter in secret:
    if letter.isalpha():
        number = (ord(letter) - ord("A") - shift) % 26
        message = message + chr(number + ord("A"))
    else:
        message = message + letter

print(message)

When you run it, it prints:

PELICAN