a = raw_input()

b = raw_input()

c1 = int(str(a), 2)#2进制转化为10进制

c2 = int(str(b), 2)

c = c1 ^ c2#按位异或

c = bin(int(str(c), 10))#10进制转换2进制

c =str(c)

c = c[2:]

rr = [];

if len(str(a)) != len(c):

c = '0' * (len(str(a)) - len(c)) + c

for i in range(len(c)):

if c[i] =='0':

rr.append('1')

else:

rr.append('0')

rr = str(rr)

rr = rr.replace('[','')

rr = rr.replace(']','')

rr = rr.replace(',','')

rr = rr.replace('\'','')

rr = rr.replace(' ','')