#!/usr/bin/env python2.7

key = raw_input()
ciphertext = raw_input()
assert len(ciphertext) % 2 == 0

key = map(ord, key)

plaintext = []
ki = 0
for i in xrange(0, len(ciphertext), 2):
    x = int(ciphertext[i:i+2], 16)
    k = key[ki % len(key)]
    x = x ^ k
    plaintext.append(x)
    ki += 1

plaintext = map(chr, plaintext)
print "".join(plaintext)