#include<iostream>
#include<vector>
#include<string>
#include<cstring>
#include<algorithm>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<queue>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;

const ll INF = 1000000000ll * 1000000000ll;
ll B[100010];
int N;

int main() {
	cin >> N;
	for (int i = 0; i < N; i++)
		cin >> B[i];
	ll low = 1, high = INF;
	ll now = 0;
	for (int i = 0; i < N; i++) {
		if (i%2 == 0) now = B[i]-now;
		else now = now-B[i];
		if ((i/2)%2 == 0) high = min(high, now-1);
		else low = max(low, -now+1);
	}
	if (low > high) cout << -1 << endl;
	else {
		cout << N+1 << endl;
		cout << low << endl;
		ll now = low;
		for (int i = 0; i < N; i++) {
			if (i%2 == 0) now = B[i]-now;
			else now = now-B[i];
			cout << now << endl;
		}
	}
	return 0;
}