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

const ll MAX = 1e18;
ll b[100010];

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 l = 1, r = MAX;
	for(int i = 0; i < n; i++) {
		ll nl, nr;
		// add
		if(i % 2 == 0) {
			nl = max(b[i] - r, 1LL);
			nr = b[i] - l;
		}
		// sub
		else {
			nl = max(l - b[i], 1LL);
			nr = r - b[i];
		}
		l = nl, r = nr;
		if(l > r) {
			cout << -1 << endl;
			return 0;
		}
	}

	cout << n + 1 << endl;
	vector<ll> a;
	ll v = l;
	a.push_back(v);
	for(int i = n - 1; i >= 0; i--) {
		// add
		if(i % 2 == 0) {
			v = b[i] - v;
		}
		// sub
		else {
			v += b[i];
		}
		a.push_back(v);
	}
	reverse(a.begin(), a.end());
	for(auto aa : a) {
		cout << aa << endl;
	}
}