a = input()
b = input()

a = "0" * (30-len(a)) + a
b = "0" * (30-len(b)) + b

c = [None] * 30

for i in range(30):
    if a[i] == b[i]:
        c[i] = "0"
    else:
        c[i] = "1"

c = "".join(c)

c = c.lstrip("0")

print(c)