#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll MAX = 1e18;

ll a[100000];
ll b[100000];

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);

	int n;
	cin >> n;
	for(int i = 0; i < n; i++) {
		cin >> b[i];
	}

	ll min_a = 1, max_a = b[0] - 1;
	for(int i = 1; i < n; i++) {
		if(i % 2 == 0) {
			min_a = b[i] - (max_a - 1);
			max_a = b[i] - (min_a - 1);
		} else {
			min_a -= b[i];
			max_a -= b[i];
		}
		min_a = max(1LL, min_a);
		max_a = min(MAX, min_a);
	}
	if(max_a <= 0 || min_a > MAX || max_a < min_a) {
		cout << -1 << endl;
		return 0;
	}
	cout << n + 1 << endl;
	a[n] = min_a;
	for(int i = n - 1; i >= 0; i--) {
		if(i % 2 == 0) {
			a[i] = b[i] - a[i + 1];
		} else {
			a[i] = b[i] + a[i + 1];
		}
	}

	for(int i = 0; i < n + 1; i++) {
		cout << a[i] << endl;
	}
}