//初項a1における条件式を考えればよい。
#include <iostream>
#include <algorithm>
#define int long long
using namespace std;

int n;
int b[100000];

signed main() {
	int i;
	
	cin >> n;
	for (i = 0; i < n; i++) cin >> b[i];
	
	int low = 1, high = 1000000000000000000;
	int val = 0;
	for (i = 0; i < n; i++) {
		if (i % 2 == 0) val = b[i] - val;
		else val = val - b[i];
		if (i % 4 < 2) high = min(high, val - 1);
		else low = max(low, -val + 1);
	}
	if (low > high) { cout << -1 << endl; return 0; }

	cout << n + 1 << endl << low << endl;
	val = low;
	for (i = 0; i < n; i++) {
		if (i % 2 == 0) val = b[i] - val;
		else val = val - b[i];
		cout << val << endl;
	}
	return 0;
}