#include <bits/stdc++.h>
using namespace std;
int mov[4][2] = {
    -1, 0, 0, 1, 1, 0, 0, -1,
};
template <typename T>
struct number_iterator : std::iterator<random_access_iterator_tag, T> {
  T v;
  number_iterator(T _v) : v(_v) {}
  operator T&() { return v; }
  T operator*() const { return v; }
};
template <typename T>
struct number_range {
  T b, e;
  number_range(T b, T e) : b(b), e(e) {}
  number_iterator<T> begin() { return b; }
  number_iterator<T> end() { return e; }
};
template <typename T>
number_range<T> range(T e) {
  return number_range<T>(0, e);
}
template <typename T>
number_range<T> range(T b, T e) {
  return number_range<T>(b, e);
}
int int_to_lowbit(int n) {
  int a = n & (n - 1);
  return n - a;
}
int main() {
  int sum, limit;
  cin >> sum >> limit;
  set<pair<int, int> > S;
  for (int i : range(1, limit + 1)) {
    int a = int_to_lowbit(i);
    S.insert(make_pair((-a), (i)));
  }
  int total = 0;
  vector<int> ans;
  for (auto a : S) {
    int lowbit = -a.first;
    int n = a.second;
    if (total + lowbit <= sum) {
      total += lowbit;
      ans.push_back(n);
    }
    if (total == sum) break;
  }
  if (total == sum && 1 <= ans.size() && ans.size() <= 100000) {
    cout << ans.size() << endl;
    for (auto a : ans) cout << a << " ";
    cout << endl;
  } else
    cout << -1 << endl;
  return 0;
}
