#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
const int mod = 1000000007;
const int inf = 1000000009;
const long long INF = 1000000000000000009;
const long long big = 1000000000000000;
const long double eps = 0.000000000000000000001;
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long int u, v;
  cin >> u >> v;
  if (u > v || (u & 1) != (v & 1))
    cout << -1;
  else if (u == v && v == 0)
    cout << 0;
  else if (u == v)
    cout << 1 << " " << u;
  else {
    long long int x = (v - u) / 2;
    if ((x & u) == 0)
      cout << 2 << "\n" << x << " " << x + u;
    else
      cout << 3 << "\n" << u << " " << x << " " << x;
  }
  return 0;
}
