abc = "abcdefghijklmnopqrstuvwxyz"

def encoding(cChar):

    i = -1

    for x in range(0, len(abc)):

        if abc[x] == cChar:

            i = x

            break

    

    if i == -1:

        return cChar

    

    return abc[i - 2]

text = input("Give me a message to encode:")

sMsg = ""

for x in range (0, len(text)):

    sMsg = sMsg + encoding(text[x])

    

print(sMsg)