#include <bits/stdc++.h>
using namespace std;

int main()
{
    int a, b;
    cin >> a >> b;
    int cnt = 0;
    for (int i=0;i<31;++i)
    {
        int x, y; 
        x = (a>>i)&1;
        y = (b>>i)&1;
        if (x == y) continue;
        else if (x == 0 and y == 1) ++cnt;
        else {
            cout << 0 << endl;
            return 0;
        }
    }
    if (cnt == 0)
    {
        cout << 1 << endl;
        return 0;
    }
    int ans = 1;
    --cnt;
    while (cnt--) ans *= 2;
    cout << ans << endl;
    return 0;
}