#include <bits/stdc++.h>
using namespace std;
const long long N = 100001;
long long A[N];
bool vis[N];
long long ex[20];
int main() {
  ex[0] = 1;
  for (long long i = 1; i < 20; i++) {
    ex[i] = ex[i - 1] * 2;
  }
  for (long long i = 1; i < N; i++) {
    for (long long j = 0; j < 20; j++) {
      if ((i >> j) & 1 == 1) {
        A[i] = ex[j];
        break;
      }
    }
  }
  long long sum, lim;
  cin >> sum >> lim;
  vector<long long> v;
  map<long long, vector<long long> > puede;
  for (long long i = 1; i <= lim; i++) {
    v.push_back(A[i]);
    puede[A[i]].push_back(i);
  }
  sort(v.begin(), v.end());
  vector<long long> rep;
  while (sum > 0) {
    vector<long long>::iterator upp;
    upp = upper_bound(v.begin(), v.end(), sum);
    long long pos = upp - v.begin() - 1;
    sum -= v[pos];
    vector<long long> aux;
    aux = puede[v[pos]];
    for (long long i = 0; i < aux.size(); i++) {
      if (!vis[aux[i]]) {
        vis[aux[i]] = true;
        rep.push_back(aux[i]);
        break;
      }
    }
    v.erase(v.begin() + pos);
    long long sz = v.size();
    if (sz == 0) {
      break;
    }
  }
  if (sum == 0) {
    long long sz = rep.size();
    cout << sz << endl;
    for (long long i = 0; i < sz; i++) {
      cout << rep[i] << " ";
    }
    cout << endl;
  } else {
    cout << -1 << endl;
  }
  return 0;
}
