#!/usr/bin/env python


def main():
    output = []
    raw_message = "Test Message".upper()
    keyword = "Keyword".upper()
    while not keyword.isalpha():
        keyword = input("Enter a valid word(only letters!)")
    keyword_counter = 0
    for character in raw_message:
        if character in "ABCDEFGHIJKLMNOPQRSTUVWXYZ":
            keyword_letter = keyword[keyword_counter]
            answer = (ord(character) - 65) + (ord(keyword_letter) - 64)
            answer = answer % 26
            answer = answer + 65
            answer = chr(answer)
            output.append(answer)
        else:
            output.append(character)
    keyword_counter = keyword_counter + 1
    if keyword_counter > (len(keyword) - 1):
        keyword_counter = 0
    print("".join(output))


if __name__ == '__main__':
    main()