#include <bits/stdc++.h>
using namespace std;
void yala_bena() {
  cin.tie(0);
  std::ios::sync_with_stdio(0);
}
const int m_r = 999999;
int k = -1;
int bestsum, limit;
vector<long long> ans;
int binary(int number) {
  while (number) {
    k++;
    if (number % 2) return k;
    number /= 2;
  }
}
void sum_it_up(int sum, int index, vector<int> p) {
  if (sum + ans[index] <= bestsum) {
    sum += ans[index];
    p.push_back(index + 1);
  }
  if (sum == bestsum) {
    cout << p.size() << endl;
    for (int i = 0; i < p.size(); i++) {
      if (i == p.size() - 1)
        cout << p[i] << endl;
      else
        cout << p[i] << " ";
    }
    exit(0);
  }
  for (int i = index + 1; i < ans.size(); i++) {
    if (sum + ans[i] <= bestsum) sum_it_up(sum, i, p);
  }
}
int main() {
  yala_bena();
  cin >> bestsum >> limit;
  for (int i = limit; i >= 1; i--) {
    int a = (int)pow(2, binary(i));
    k = -1;
    if (a <= bestsum) bestsum -= a, ans.push_back(i);
  }
  if (bestsum == 0) {
    cout << ans.size() << endl;
    for (int i = 0; i < ans.size(); i++)
      i == ans.size() - 1 ? cout << ans[i] << endl : cout << ans[i] << " ";
    return 0;
  }
  cout << -1 << endl;
}
