#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, m;
  cin >> n >> m;
  if (n == 0 && m == 0) {
    cout << "0" << endl;
    return 0;
  }
  if (n > m) {
    cout << "-1" << endl;
    return 0;
  }
  if (n == m) {
    cout << 1 << endl;
    cout << n << endl;
    return 0;
  }
  if ((m - n) % 2 != 0) {
    cout << "-1" << endl;
    return 0;
  }
  long long u = (m - n) >> 1;
  if (n + u == (n ^ u)) {
    cout << 2 << endl;
    cout << n + u << " " << u << endl;
    return 0;
  } else {
    cout << "3" << endl;
    cout << n << " " << u << " " << u << endl;
    return 0;
  }
  return 0;
}
