A,B=map(int,input().split())
AND=[]
OR =[]
for i in range(31):
    AND.append(A//(2**(30-i)))
    A%=(2**(30-i))
    OR.append(B//(2**(30-i)))
    B%=(2**(30-i))
#print(AND)
#print(OR)
cnt=0
for i in range(31):
    if AND[i]>OR[i]:
        print(0)
        exit()
    elif AND[i]<OR[i]:
        cnt+=1
print(max(1,2**(cnt-1)))