#include <bits/stdc++.h>
using namespace std;
long long gcd(long long a, long long b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long binExp(long long x, long long n) {
  long long r = 1;
  while (n > 0) {
    if (n % 2 == 1) r = r * x;
    x = x * x;
    n = n / 2;
  }
  return r;
}
long long modbinExp(long long x, long long n, long long M) {
  long long r = 1;
  while (n > 0) {
    if (n % 2 == 1) r = (r * x) % M;
    x = (x * x) % M;
    n = n / 2;
  }
  return r;
}
long long fnc(long long n) {
  for (long long i = 0; i < 31; i++)
    if (n & (1 << i)) return i;
}
map<long long, vector<long long> > mp;
void solve() {
  long long sum, limit;
  cin >> sum >> limit;
  vector<long long> ans;
  for (long long i = 1; i <= limit; i++) {
    long long pos = fnc(i);
    mp[pos].push_back(i);
  }
  long long re = 0;
  for (long long j = 31; j >= 0; j--) {
    if ((1 << j) & sum) re++;
    if (mp[j].size() >= re) {
      for (long long k = 0; k < re; k++) ans.push_back(mp[j][k]);
      re = 0;
    } else {
      for (long long k = 0; k < mp[j].size(); k++) ans.push_back(mp[j][k]);
      re = re - mp[j].size();
    }
    re *= 2;
  }
  if (re)
    cout << -1;
  else {
    cout << ans.size() << "\n";
    for (long long k = 0; k < ans.size(); k++) cout << ans[k] << " ";
  }
}
int main() {
  ios_base::sync_with_stdio(false);
  long long t;
  t = 1;
  while (t--) {
    solve();
  }
}
