A,B = map(int,input().split())
A = bin(A)[2:]
A = "0"*(31-len(A))+A
B = bin(B)[2:]
B = "0"*(31-len(B))+B
X = [-1]*31
Y = [-1]*31
for i in range(31):
    if B[i]=="0":
        X[i] = 0
        Y[i] = 0
flag = 0
for i in range(31):
    if A[i]=="1":
        if X[i]<0 and Y[i]<0:
            X[i] = 1
            Y[i] = 1
        else:
            flag = 1
            break
if flag==1:
    print(0)
else:
    cnt = 0
    for i in range(31):
        if X[i]<0:
            cnt += 1
    if cnt==0:
        print(1)
    else:
        print(pow(2,cnt-1))