D. Ehab the Xorcist

#include "stdafx.h"
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <queue>
#include <map>
#include <sstream>
#include <cstdio>
#include <cstring>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <deque>
#include <bitset>
//#include <unordered_set>
//#include <unordered_map>
//#include <bits/stdc++.h>
//#include <xfunctional>
#define ll  long long
#define PII  pair<int, int>
using namespace std;
int dir[5][2] = { { 0,1 } ,{ 0,-1 },{ 1,0 },{ -1,0 } ,{ 0,0 } };
const long long INF = 0x7f7f7f7f7f7f7f7f;
const int inf = 0x3f3f3f3f;
const double pi = 3.14159265358979;
const int mod = 1e9 + 7;
const int maxn = 2005;
//if(x<0 || x>=r || y<0 || y>=c)
//1000000000000000000

inline ll read()
{
    ll x = 0; bool f = true; char c = getchar();
    while (c < ‘0‘ || c > ‘9‘) { if (c == ‘-‘) f = false; c = getchar(); }
    while (c >= ‘0‘ && c <= ‘9‘) x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
    return f ? x : -x;
}

int main() 
{
    ll u, v;
    cin >> u >> v;
    ll d = v - u;
    if (d < 0 || (d % 2))
    {
        cout << -1 << endl;
        return 0;
    }
    if (!d)
    {
        if (!u)
            cout << 0 << endl;
        else
        {
            cout << 1 << endl;
            cout << u << endl;
        }
    }
    else
    {
        ll h = d >> 1;
        if ((h&u) == 0)
        {
            cout << 2 << endl;
            cout << h << " " << (h^u) << endl;
        }
        else
        {
            cout << 3 << endl;
            cout << h << " " << h << " " << u << endl;
        }
    }
    return 0;
}