import sys
if len(sys.argv) != 3:
    print "Usage: python "+sys.argv[0]+" <encrypted_message> <user_name>"
    exit(1)
encrypted_message = sys.argv[1]
user_name = sys.argv[2]

import base64
result = []
for i, c in enumerate(base64.b64decode(encrypted_message)):
    result.append(chr(ord(c) ^ ord(user_name[i % len(user_name)])))
print ''.join(result)