#include <bits/stdc++.h>
using namespace std;
int i, j, k, m, n, sum, lim, mm;
int a[100];
int lowbit(int x) { return x & (-x); }
int ans[101000];
int main() {
  cin >> sum >> lim;
  memset(a, 0, sizeof(a));
  mm = 0;
  for (i = 1; i <= lim; i++) {
    k = lowbit(i);
    mm += k;
    a[(int)(log(k + 0.5) / log(2))]++;
  }
  if (mm < sum)
    cout << -1 << endl;
  else {
    int top = 0;
    for (i = 17; i >= 0; i--) {
      int now = 0;
      while (sum >= (1 << i) && a[i]) {
        a[i]--;
        sum -= (1 << i);
        ans[++top] = (1 << i) + now * (1 << (i + 1));
        now++;
      }
    }
    printf("%d\n", top);
    for (i = 1; i <= top; i++) cout << ans[i] << " ";
    cout << endl;
  }
  return 0;
}
