#include <bits/stdc++.h>
using namespace std;
const int INF = (int)1e9;
const int mod = (int)1e9 + 7;
const int MAX = (int)1e5 + 5;
int sum, limit;
long long cnt;
vector<int> store[MAX];
void build() {
  for (int i = (1); i < (limit + 1); ++i) {
    int p = 0, v = 1;
    while (!(v & i)) {
      p++;
      v <<= 1;
    }
    store[p].push_back(i);
    cnt += v;
  }
  return;
}
void read() {
  cin >> sum >> limit;
  return;
}
vector<int> ans;
void sol() {
  if (cnt < sum) {
    puts("-1");
    return;
  }
  int cur = 20, num = 1;
  while (!(sum & (1 << cur))) cur--;
  while (sum != 0) {
    if ((int)store[cur].size() >= num) {
      sum -= num * (1 << cur);
      for (int i = 0; i < (num); ++i) ans.push_back(store[cur][i]);
      num = 0;
    } else {
      sum -= (int)store[cur].size() * (1 << cur);
      for (int x : store[cur]) ans.push_back(x);
      num -= (int)store[cur].size();
    }
    num <<= 1;
    cur--;
    if (sum & (1 << cur)) num++;
  }
  printf("%d\n", (int)ans.size());
  for (int x : ans) printf("%d ", x);
  return;
}
int main(void) {
  read();
  build();
  sol();
  return 0;
}
