#include "iostream" 
using namespace std;

int N;
long long int num[100000];
long long int ans[100001];


int main() {
	cin >> N;
	for (int i = 0; i < N; i++) {
		cin >> num[i];
	}
	ans[0] = 1;
	for (int i = 1; i < N + 1; i++) {
		if (i % 2 == 1) {
			ans[i] = num[i - 1] - ans[i - 1];
		}
		else {
			ans[i] = ans[i - 1] - num[i - 1];
		}
		if (ans[i] <= 0) {
			cout << "-1\n";
			return 0;
		}
	}
	cout << N + 1 << "\n";
	for (int i = 0; i < N + 1; i++) {
		cout << ans[i] << "\n";
	}
	return 0;
}