from sys import setrecursionlimit, stdin
from collections import defaultdict, deque, Counter
from itertools import permutations, combinations, product
from functools import lru_cache
from bisect import bisect_left, bisect_right
from heapq import heappush, heappop
from copy import copy, deepcopy
from decimal import Decimal
from random import random, randrange

# from pypyjit import set_param
# set_param('max_unroll_recursion=-1')

setrecursionlimit(1 << 20)
readline = stdin.readline
INF = 10 ** 18
MOD = 998244353
# MOD = 1000000007
ALP = 26
''' Input '''
def I(): return int(readline())
def ST(): return readline()[:-1]
def LI(): return list(map(int, readline().split()))
def LII(): return list(map(lambda x: int(x) - 1, readline().split()))
def LF(x, func): return [func() for _ in [0] * x]
def SPI(): return map(int, readline().split())
def SPII(): return map(lambda x: int(x) - 1, readline().split())
def FIE(x): return [readline()[:-1] for _ in [0] * x]

''' Array '''
def cmin(dp, i, x):
    if x < dp[i]: dp[i] = x
def cmax(dp, i, x):
    if x > dp[i]: dp[i] = x

''' Alphabet '''
def alp_a_to_i(s): return ord(s) - ord('a')
def alp_A_to_i(s): return ord(s) - ord('A')
def alp_i_to_a(i): return chr(ord('a') + i)
def alp_i_to_A(i): return chr(ord('A') + i)

''' Other'''
def nynx(y, x, H, W): return [(y + dy, x + dx) for dy, dx in [(-1, 0), (1, 0), (0, -1), (0, 1)] if 0 <= y + dy < H and 0 <= x + dx < W]
def gen(x, *args):
    if len(args) == 1: return [x] * args[0]
    if len(args) == 2: return [[x] * args[1] for _ in [0] * args[0]]
    if len(args) == 3: return [[[x] * args[2] for _ in [0] * args[1]] for _ in [0] * args[0]]
    if len(args) == 4: return [[[[x] * args[3] for _ in [0] * args[2]] for _ in [0] * args[1]] for _ in [0] * args[0]]

''' Output '''
def pprint(E): 
    print()
    for e in E: print(e)
def Yes(): print("Yes")
def No(): print("No")
def YES(): print("YES")
def NO(): print("NO")
def yn(x): print("Yes" if x else "No")
def YN(x): print("YES" if x else "NO")
###############################################################################################

A = ST()
B = ST()
N = max(len(A), len(B))
A = '0' * N + A
B = '0' * N + B
A = A[-N:]
B = B[-N:]
ans = 0
for i in range(N):
    a = int(A[N - i - 1])
    b = int(B[N - i - 1])
    if a + b == 1:
        ans += 1 << i

print(ans)