#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 2;
const long long mod = 1e9 + 7;
long long powermodm(long long x, long long n, long long M) {
  long long result = 1;
  while (n > 0) {
    if (n % 2 == 1) result = (result * x) % M;
    x = (x * x) % M;
    n = n / 2;
  }
  return result;
}
long long power(long long x, long long y) {
  long long z = 1;
  while (y) {
    if (y % 2 == 1) z = (z * x);
    y /= 2;
    x = (x * x);
  }
  return z;
}
long long gcd(long long a, long long b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long lcm(long long a, long long b) {
  return (max(a, b) / gcd(a, b)) * min(a, b);
}
int main() {
  long long u, v;
  cin >> u >> v;
  if (u > v)
    cout << -1;
  else if (u == v && u == 0)
    cout << 0;
  else if (u == v)
    cout << 1 << endl << u;
  else if ((v - u) % 2)
    cout << -1;
  else if (((u + (v - u) / 2) ^ ((v - u) / 2)) == u)
    cout << 2 << endl << u + (v - u) / 2 << " " << (v - u) / 2;
  else
    cout << 3 << endl << u << " " << (v - u) / 2 << " " << (v - u) / 2;
  return 0;
}
