Codeforces Round #628 (Div. 2) D. Ehab the Xorcist（异或，思维题）

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;

int main()
{    
    ll u,v;cin>>u>>v;
    ll a=u,b=(v-u)/2;
    if(u==0&&v==0){
        cout<<"0";
    }else if(v<u||(v-u)%2){
        cout<<"-1";
    }else if(u==v){
        cout<<"1\n";
        cout<<a<<endl;
    }else if(((a+b)^b)==u){
        cout<<"2\n";
        cout<<a+b<<‘ ‘<<b<<endl;
    }else{
        cout<<"3\n";
        cout<<a<<‘ ‘<<b<<‘ ‘<<b<<endl;
    }
    return 0;
}