import sys
#sys.setrecursionlimit(10 ** 6)
INF = float('inf')
#10**20,2**63に変えるのもあり
MOD = 10**9 + 7
MOD2 = 998244353
from collections import defaultdict
def ceil(A,B):
    return -(-A//B)
def solve():
    def II(): return int(sys.stdin.readline())
    def LI(): return list(map(int, sys.stdin.readline().split()))
    def LC(): return list(input())
    def IC(): return [int(c) for c in input()]
    def MI(): return map(int, sys.stdin.readline().split())
    A = IC()
    B = IC()
    A.reverse()
    B.reverse()
    if(len(A)<len(B)):
        A += [0]*(max(len(A),len(B))-min(len(A),len(B)))
    else:
        B += [0]*(max(len(A),len(B))-min(len(A),len(B)))
    #print(A,B)
    N = len(A)
    C = [0]*N
    for i in range(len(A)):
        if(A[i]+B[i]==2):
            C[i]=0
        else:
            C[i]=A[i]+B[i]
    Ans = 0
    for i in range(N):
        Ans+=2**i*C[i]
    print(Ans)
    return
solve()