A = str(input())
B = str(input())

a = []
b = []
for i in range(len(A) - 1, -1, -1):
  a.append(A[i])

for i in range(len(B) - 1, -1, -1):
  b.append(B[i])

c = []
for i in range(min(len(A), len(B))):
  c.append((int(a[i]) + int(b[i])) % 2)

if len(A) > len(B):
  for i in range(len(B), len(A)):
    c.append(int(a[i]))
else:
  for i in range(len(A), len(B)):
    c.append(int(b[i]))

p = 0
ans = 0

for i in range(len(c)):
  ans += pow(2, p) * c[i]
  p += 1
print(ans)