#include<bits/stdc++.h>
using namespace std;
#define rep(i,a,b) for(int i=a;i<b;i++)





typedef long long ll;
#define INF 1LL<<60
int N; ll B[101010];
//-----------------------------------------------------------------------------------
vector<ll> simulate(ll a0) {
    vector<ll> res;

    res.push_back(a0);
    rep(i, 0, N) {
        if (i % 2 == 0) res.push_back(B[i] - res[i]);
        else res.push_back(res[i] - B[i]);
    }

    return res;
}
//-----------------------------------------------------------------------------------
int main() {
    cin >> N; rep(i, 0, N) scanf("%lld", &B[i]);

    vector<ll> a;
    
    a = simulate(0);

    /*rep(i, 0, N + 1) printf("%lld\n", a[i]);
    cout << endl;*/

    ll L = 1, R = INF;
    rep(i, 0, N + 1) {
        if (i % 4 == 0 || i % 4 == 3) {
            if (a[i] < 1) {
                L = max(L, 1 - a[i]);
            }
        } else {
            if (a[i] <= 0) {
                printf("-1\n");
                return 0;
            }
            R = min(R, a[i] - 1);
        }
    }

    if (R < L) {
        printf("-1\n");
        return 0;
    }

    a = simulate(L);
    cout << N + 1 << endl;
    rep(i, 0, N + 1) printf("%lld\n", a[i]);
}