#include <iostream>
#include <vector>
#include <map>
#include <set>
#include <utility>
#define ll long long
#define vii vector<vector<int>>
#define pii pair<int, int>
using namespace std;
vector<ll> solve(ll u, ll v) {
    if (u > v || (u & 1) != (v & 1))
        return {-1};
    else if (u == 0 && v == 0)
        return {};
    else if (u == v)
        return {u};
    else if ((u & ((v - u) / 2)) == 0)
        return {u + (v - u) / 2,  (v - u) / 2};
    else
        return {u, (v - u) / 2 , (v - u) / 2};
}
int main() {
    ll u, v;
    cin >> u >> v;
    auto ans = solve(u, v);
    if (ans.empty())
        cout << 0;
    else if (ans[0] == -1)
        cout << -1;
    else {
        cout << ans.size() << endl;
        for (int k : ans)
            cout << k << ' ';
    }
}