#!/usr/bin/python3

# 1. Par: hexadecimal STRING
# 2. Par: hexadecimal STRING
# return STRING

#---------------------------------------------
def hexxor(a,b):
    res = ""
    i = 0
    X = Y = 0
    if len(a) > len(b):
        for (x,y) in zip (a[:len(b)] , b) :
             i = i + 1
             X = X*16 + int(x,16)
             Y = Y*16 + int(y,16)
             e = hex(X^Y)[2:]
             res += e	
             X = Y = 0
    else:
        for (x,y) in zip (a , b[:len(a)]) :
             i = i + 1
             X = X*16 + int(x,16)
             Y = Y*16 + int(y,16)
             e = hex(X^Y)[2:]
             res += e	
             X = Y = 0
    return res

#---------------------------------------------
def printhex(a):
    import binascii
    if len(a)%2 != 0 :
        a = a+"0"
    print (binascii.unhexlify(a))

def converthex(a):
    import binascii
    if len(a)%2 != 0 :
        a = a+"0"
    return binascii.unhexlify(a)

def convert_to_hex(s):
    return s.encode('hex')

#---------------------------------------------

import sys
if len(sys.argv) == 3:
    RESULT = hexxor(sys.argv[1], sys.argv[2])
    print (str(converthex(RESULT))[2:-1])
