#include <bits/stdc++.h>
using namespace std;
const long long m = 1000000000000000000;
int n; long long b[100009];
int main() {
	scanf("%d", &n);
	for(int i = 0; i < n; i++) scanf("%lld", &b[i]);
	long long l = 1, r = m;
	for(int i = 0; i < n; i++) {
		if(i & 1) {
			long long t = l;
			l = max(1LL, b[i] - r);
			r = min(m, b[i] - t);
		}
		else {
			l = max(1LL, l - b[i]);
			r = min(m, r - b[i]);
		}
	}
	if(l > r) puts("-1");
	else {
		printf("%d\n", n + 1);
		for(int i = 0; i < n + 1; i++) {
			printf("%lld\n", l);
			if(i & 1) l -= b[i];
			else l = b[i] - l;
		}
	}
	return 0;
}