#include <bits/stdc++.h>
using namespace std;
void fast() {
  cin.tie(0);
  cin.sync_with_stdio(0);
}
vector<string> v;
bool check(string s) {
  int freq[26] = {0};
  for (int i = 0; i < s.length(); ++i) {
    freq[s[i] - 'A']++;
    if (freq[s[i] - 'A'] > 1) return false;
  }
  return true;
}
long long fastExpo(long long a, long long b) {
  if (!b) return 1;
  long long half = fastExpo(a, b / 2);
  long long ans = (half * half);
  if (b & 1) return (ans * a);
  return ans;
}
int main() {
  fast();
  long long a, b;
  cin >> a >> b;
  if (a == b) {
    if (a == 0)
      cout << a;
    else
      cout << 1 << "\n" << a;
  } else if (a > b || (b - a) % 2 != 0)
    cout << -1;
  else {
    long long temp = (b - a) / 2;
    if ((((temp + a) ^ temp) == a))
      cout << 2 << "\n" << temp + a << " " << temp;
    else
      cout << 3 << "\n" << a << " " << temp << " " << temp;
  }
}
