#include<bits/stdc++.h>
int main(){
    unsigned a,b;std::cin>>a>>b;
    if(a==b){
        std::cout<<1<<std::endl;
        return 0;
    }
    unsigned ans=1;
    for(;a||b;a>>=1,b>>=1){
        if(a&1u&&!(b&1u)){
            std::cout<<0<<std::endl;
            return 0;
        }
        if((a&1u)!=(b&1u))ans<<=1;
    }
    ans>>=1;
    std::cout<<ans<<std::endl;
}