#include <bits/stdc++.h>
using namespace std;
template <class T>
void pp(T v) {
  for (__typeof((v).begin()) it = (v).begin(); it != (v).end(); ++it)
    cout << *it << ' ';
  cout << endl;
}
template <class T>
void pp(T v, int n) {
  for (int i = 0; i < (int)n; i++) cout << v[i] << ' ';
  cout << endl;
}
template <class T>
inline void chmax(T &a, const T b) {
  a = max(a, b);
}
template <class T>
inline void chmin(T &a, const T b) {
  a = min(a, b);
}
const int INF = 1 << 28;
const double EPS = 1.0e-9;
static const int dx[] = {1, 0, -1, 0}, dy[] = {0, -1, 0, 1};
int main(void) {
  int sum, limit;
  cin >> sum >> limit;
  vector<int> num[20];
  int base[20];
  base[1] = 1;
  for (int i = 2; i < 20; i++) {
    base[i] = base[i - 1] * 2;
  }
  int max_idx = 1;
  for (int i = 1; i <= limit; i++) {
    int pos = 1;
    for (int j = 0; j < 30; j++) {
      if ((1 << j) & i) {
        pos = j + 1;
        break;
      }
    }
    num[pos].push_back(i);
    chmax(max_idx, pos);
  }
  vector<int> ans;
  for (int i = max_idx; i >= 1; i--) {
    while (sum >= base[i] && num[i].empty() == false) {
      ans.push_back(num[i].back());
      num[i].pop_back();
      sum -= base[i];
    }
  }
  if (sum > 0) {
    cout << -1 << endl;
  } else {
    cout << ans.size() << endl;
    pp(ans);
  }
  return 0;
}
