PY

suan=[]
naple=[]
a=input();b=input()
list_and_tuple=list(zip(a,b))
for tuples in list_and_tuple:
    tuples=list(tuples)
    naple.append(tuples)
for Lst in naple:
    Lst=list(map(int,Lst))
    end=Lst[0]^Lst[-1]
    suan.append(end)
for i in suan:
    print(i,end='')