#include <bits/stdc++.h>
using namespace std;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  ;
  long long a, b;
  cin >> a >> b;
  if (b < a || (b - a) % 2)
    cout << -1 << endl;
  else if (b == a && a == 0)
    cout << 0 << endl;
  else if (b == a)
    cout << 1 << endl << a;
  else {
    long long x = 0, cnt = 1, pp = b - a;
    while (cnt <= pp) cnt *= 2;
    cnt /= 2;
    while (true) {
      if (cnt * 2 <= pp) {
        x += cnt;
        pp -= cnt * 2;
      }
      cnt /= 2;
      if (pp == 0) break;
    }
    long long tt = a ^ x;
    if (tt == a + x)
      cout << 2 << endl << a + x << ' ' << x << endl;
    else
      cout << 3 << endl << a << ' ' << x << ' ' << x << endl;
  }
}
