#include <stdio.h>
#include <string>
#include <cstring>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
#include <assert.h>
#pragma warning(disable:4996) 
 
typedef long long ll;
#define MIN(a, b) ((a)>(b)? (b): (a))
#define MAX(a, b) ((a)<(b)? (b): (a))
#define LINF 9223300000000000000
#define INF 2140000000
const long long MOD = 1000000007;
//const long long MOD = 998244353;
using namespace std;


int main(int argc, char* argv[])
{
    ll a,b;
    scanf("%lld%lld", &a, &b);

    ll ans=1;
    int i;
    for(i=31; i>=0; i--) {
        int tmp0=((a & (1<<i))? 1: 0);
        int tmp1=((b & (1<<i))? 1: 0);
        if(tmp0>tmp1) {
            printf("0\n"); return 0;
        }
        if(tmp0<tmp1) {
            ans*=2;
        }
    }
    if(ans>1) ans/=2;
    printf("%lld\n", ans);

    return 0;
}