#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const ll INF = 1000000000000000000;

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int n;
	cin >> n;
	vector<ll> b(n);
	for (int i = 0; i < n; i++) cin >> b[i];
	vector<ll> a(n + 1);
	a[0] = 1;
	for (int i = 1; i <= n; i++) {
		if (i % 2 == 1) {
			a[i] = b[i - 1] - a[i - 1];
		} else {
			a[i] = a[i - 1]- b[i - 1];
		}
		
		if (a[i] <= 0 || a[i] > INF) {
			cout << -1 << endl;
			return 0;
		}
	} 
	cout << n + 1 << endl;
	for (int i = 0; i <= n; i++) {
		cout << a[i] << endl;
	}
	return 0;
}