#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=long double;
ld pie=3.141592653589793;
ll inf=300000000;
ll mod=998244353;
int main(){
    ll n;
    cin >> n;
    vector<ll>b(n);
    ll d=1000000000000000000;
    for (ll i = 0; i < n; i++)
    {
        cin >> b[i];
    }
    ll now=0;
    bool ok=true;
    ll pl=1,mn=d;
    if (n==1&&b[0]==1)
    {
        cout << -1 << endl;
        return 0;
    }
    
    for (ll i = 1; i < n; i+=2)
    {
        now*=-1;
        now+=b[i-1]-b[i];
        if ((i/2)%2==0)
        {
            if (d-now<=0||2*d<-now)
            {
                ok=false;
                break;
            }
            pl=max(pl,-d-now);
            mn=min(mn,d-now);
        }else{
            if (d-now<=0||2*d<-now)
            {
                ok=false;
                break;
            }
            pl=max(pl,now-d);
            mn=min(now+d,mn);
        }
    }
        if (!ok)
        {
            cout << -1 << endl;
            return 0;;
        }
        if (pl>mn)
        {
            cout << -1 << endl;
            return 0;
        }
        ll nn=pl;
        cout << n+1 << endl;
        cout << nn << endl;
        for (ll i = 0; i < n; i++)
        {
            if (i%2==0)
            {
                nn*=-1;
                nn+=b[i];
            }else{
                nn-=b[i];
            }
            cout << nn << endl;
        }
}