#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int u, v, v0;
  cin >> u >> v;
  v0 = v;
  long long int x[70] = {0}, help[70] = {0};
  int i = 0;
  while (u != 0) {
    x[i] = u % 2;
    help[i] = x[i];
    if (x[i]) v -= ((long long int)1 << i);
    if (v < 0) break;
    u /= 2;
    i++;
  }
  if (v < 0 or v % 2 != 0)
    cout << -1;
  else {
    i = 0;
    v /= 2;
    while (v != 0) {
      help[i] += 2 * (v % 2);
      v /= 2;
      i++;
    }
    long long int maxx = 0;
    for (i = 0; i <= 60; i++) maxx = max(help[i], maxx);
    cout << maxx << endl;
    for (i = 1; i <= maxx; i++) {
      long long int ans = 0;
      for (int j = 0; j <= 60; j++) {
        if (help[j] >= i) ans = ans + ((long long int)1 << j);
      }
      cout << ans << " ";
    }
  }
}
