a = list(map(int, input()))
b = list(map(int, input()))
if len(a) > len(b):
  a, b = b, a
res = [0] * 31
for i in range(len(a)):
  res[~i] = a[~i] ^ b[~i]
for i in range(len(a), len(b)):
  res[~i] = b[~i]
ans = 0
for i in range(31):
  ans += res[~i] << i
print(ans)