a = input()
b = input()

if len(b) > len(a):
    a, b = b, a
    
s = ''
for i in range(len(a)-len(b)):
    s += a[i]

for i in range(len(b)):
    char_a = a[len(a)-len(b)+i]
    char_b = b[i]
    if char_a == '0' and char_b == '0' or char_a == '1' and char_b == '1':
        s += '0'
    else:
        s += '1'

base = 1
ans = 0
for i in range(len(s)):
    ans += base * int(s[len(s)-1-i])
    base *= 2
    
print(ans)