#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <complex>
using namespace std;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)

typedef long long ll;
typedef uint64_t ull;
typedef pair<int, int> P;
typedef pair<int, double> Pid;
typedef pair<double, int> Pdi;
typedef pair<ll, int> Pl;
typedef pair<ll, ll> Pll;
typedef pair<int, pair<int, int>> PP;
typedef pair<P, int> PPi;
constexpr double PI = 3.1415926535897932;   // acos(-1)
constexpr double EPS = 1e-9;
constexpr int INF = 1001001001;
constexpr int mod = 1e+9 + 7;
// constexpr int mod = 998244353;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int a, b;
    cin >> a >> b;
    vector<int> pos;
    for(int i = 31; i >= 0; --i){
        if(((a >> i) & 1) && !((b >> i) & 1)){
            cout << 0 << endl;
            return 0;
        }
        if(!((a >> i) & 1) && ((b >> i) & 1))   pos.emplace_back(i);
    }
    vector<int> pow2(32);
    pow2[0] = 1;
    for(int i = 1; i < 32; ++i) pow2[i] = pow2[i - 1] * 2;
    int sz = pos.size();
    // cerr << bitset<32>(a) << "\n" << bitset<32>(b) << "\n";
    // for(int i = 0; i < sz; ++i) cerr << pos[i] << " ";
    // cerr << "\n";
    if(sz == 0) cout << 0 << endl;
    else    cout << pow2[pos.size() - 1] << endl;
}