#include <bits/stdc++.h>
using namespace std;
long long getBit(long long num, long long idx) {
  return (((num >> idx) & 1LL) == 1);
}
long long setBit(long long num, long long idx) { return (num | (1LL << idx)); }
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, m;
  cin >> n >> m;
  long long rem = m - n;
  if (n > m || rem & 1) return cout << -1, 0;
  vector<long long> v;
  v.push_back(n);
  v.push_back(0);
  v.push_back(0);
  for (int i = 1; i <= 60; ++i) {
    int rem_bit = getBit(rem, i);
    if (rem_bit) {
      int f_bit = getBit(v[0], i - 1);
      if (f_bit) {
        v[1] = setBit(v[1], i - 1);
        v[2] = setBit(v[2], i - 1);
      } else {
        v[0] = setBit(v[0], i - 1);
        v[1] = setBit(v[1], i - 1);
      }
    }
  }
  vector<long long> out;
  for (int i = 0; i < 3; ++i)
    if (v[i]) out.push_back(v[i]);
  cout << out.size() << '\n';
  for (auto it : out) cout << it << ' ';
  return 0;
}
