437B.cpp

#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <queue>
#include <map>
#include <set>
#include <iostream>
#include <sstream>
#include <cassert>
#include <fstream>
#include <cstring>
#include <numeric>
#include <ctype.h>
#define PII pair<int,int>
#define MOD 1000000009
#define exit return 0
#define inf 100000000
typedef long long ll;
#define exit return 0
#define PS system("pause")
#define S 100007
#define mx(a,b) a>b?a:b
#define R0(i,n) for (int i = 0; i < n; i++)
#define R1(i,n) for (int i = 1; i <= n; i++)
#define MS(a,x) memset(x, a, sizeof(x));
#define left (v<<1)
#define right (left|1)
#define mid ((tl+tr)>>1)
#define SZ(x) ((int)x.size())
const double eps = 1e-10;


using namespace std;
int N;
int popcount(int x){ int cnt = 0; for (int i = 0; i < N; i++){ if (x&(1 << i)){ cnt++; } }	return cnt; }
int zzz = 0;
const int NN = 1002;

int  M, L, K, X, P;
int sum, limit;
vector<int>sm;
int bit[100 * NN];
int main(){
	cin >> sum >> limit;
	X = 0;
	for (int i = limit; i > 0; i--){
		int H = (i&-i);
		if (H <= sum){
			sum -= H;
			bit[X++] = i;
		}
	}
	if (sum > 0){
		cout << -1 << endl;
		exit;
	}
	cout << X << endl;
	for (int i = 0; i < X; i++){
		cout << bit[i] << " ";
	}
	exit;
	PS;
}