from sys import stdin
input = stdin.readline
from functools import lru_cache

@lru_cache(maxsize=1000)
def next():
    x = input().rstrip()
    return(x)
def nextint():
    x = int(input())
    return(x)
def nextfloat():
    x = float(input())
    return(x)
def nextlist():
    x = list(input().rstrip().split()) 
    return(x)
def nextintlist():
    x = list(map(int, input().rstrip().split())) 
    return(x)
def nextfloatlist():
    x = list(map(float, input().rstrip().split())) 
    return(x)  
def nextlist2():
  n = int(input())  # nは入力回数
  x = [input().rstrip() for _ in range(n)]
  return(x)
def nextintlist2():
  n = int(input())  # nは入力回数
  x = [int(input()) for _ in range(n)]
  return(x)
def nextfloatlist2():
  n = int(input())  # nは入力回数
  x = [float(input()) for _ in range(n)]
  return(x)
def nextdoublelist():
    n = int(input())  # nは入力回数
    x = [list(input().rstrip().split()) for _ in range(n)]
    return(x)
def nextdoubleintlist():
    n = int(input())  # nは入力回数
    x = [list(map(int, input().rstrip().split())) for _ in range(n)]
    return(x)
def nextdoublefloatlist():
    n = int(input())  # nは入力回数
    x = [list(map(float, input().rstrip().split())) for _ in range(n)]
    return(x)
s1 = list(next())
s2 = list(str(nextint()))
s = []
a = 0
if len(s1) >= len(s2):
    for i in range(len(s1) - len(s2)):
        s2.insert(0,"0")
elif len(s1) <= len(s2):
    for i in range(len(s2) - len(s1)):
        s1.insert(0,"0")
for i in range(len(s1)):
    if int(s1[i]) + int(s2[i]) == 0:
        s += "0"
    elif int(s1[i]) + int(s2[i]) == 2:
        s += "0"
    elif int(s1[i]) + int(s2[i]) == 1:
        s += "1"
for i in range(len(s)):
    a = (a + int(s[i])) * 2
print(int(a/2))