A = list(input())
B = list(input())
N = max(len(A), len(B));num = [0] * N;ans = []
A.reverse();B.reverse()
for i in range(N):
  if i < len(A):
    num[i] += int(A[i])
  if i < len(B):
    num[i] += int(B[i])
  if num[i] < 2:
    ans.append(num[i])
  else:
    ans.append(0)
ans_num = 0
for i in range(N):
  ans_num += ans[i] * (2 ** i)
print(ans_num)