A = input()
B = input()

if len(A)>len(B):
    lon = A
    sho = B
else:
    lon = B
    sho = A

ans = 0
for i in range(0,len(sho)):
    ans += 2**i * ((int(lon[len(lon)-1-i])+int(sho[len(sho)-1-i]))%2)


for j in range(len(sho),len(lon)):
    ans += 2**j * int(lon[len(lon)-1-j])


print(ans)