#! /usr/bin/python3
import binascii
import sys
def mask(buf1, buf2):
return bytes(a^b for (a,b) in zip(buf1, buf2))
t = bytes([0]*29)
for line in sys.stdin:
line = line.strip().encode()
a = binascii.unhexlify(line)
t = mask(t, a)
print(t)