#include <bits/stdc++.h>
using namespace std;
long long a, b, lg[61], s1[61], ans[110000];
int main() {
  lg[0] = 1;
  for (long long i = 1; i <= 60; i++) lg[i] = lg[i - 1] << 1;
  scanf("%lld%lld", &a, &b);
  for (long long i = 60; i >= 0; i--)
    if (lg[i] & a) s1[i] = 1;
  b -= a;
  if (b < 0 || b & 1) {
    printf("-1\n");
    return 0;
  }
  long long k = 0;
  for (long long i = 60; i >= 0; i--) {
    long long c = b / lg[i] / 2 * 2;
    s1[i] += c;
    b -= lg[i] * c;
    k = max(k, s1[i]);
  }
  printf("%lld\n", k);
  for (long long i = 1; i <= k; i++) {
    long long ans = 0;
    for (long long i = 60; i >= 0; i--) {
      if (s1[i]) {
        s1[i] -= 1;
        ans += lg[i];
      }
    }
    printf("%lld ", ans);
  }
  return 0;
}
