import sys
A,B=map(int,input().split())
s=bin(A)[2:]
t=bin(B)[2:]
a=len(s)
b=len(t)
x=["0"]*max(a,b)
y=["0"]*max(a,b)
for i in range(a):
    if s[i]=="1":
        x[i]="1"
        y[i]="1"
        if t[i]=="0":
            print(0)
            sys.exit()
print(2**(s.count("0")-1))