#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using PII = pair<int, int>;
using VI = vector<int>;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  ll u, v;
  cin >> u >> v;
  if (u > v || (v - u) & 1) {
    cout << -1 << endl;
    return 0;
  }
  if (u == v) {
    if (u) {
      cout << 1 << endl << u << endl;
    } else {
      cout << 0 << endl;
    }
    return 0;
  }
  ll c = (v - u) / 2;
  if ((c & u) == 0) {
    cout << 2 << endl;
    cout << c << ' ' << (c ^ u) << endl;
    return 0;
  }
  cout << 3 << endl;
  cout << u << ' ' << c << ' ' << c << endl;
  return 0;
}
