#define _CRT_SECURE_NO_WARNINGS
#include<sstream>
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<climits>
#include<cmath>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<queue>
#include<numeric>
#include<functional>
#include<algorithm>
#include<bitset>
#include<tuple>
#include<unordered_set>
#include<random>
using namespace std;
#define INF (1<<29)
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(v) v.begin(),v.end()
#define uniq(v) v.erase(unique(all(v)),v.end())



long long maxv = 1000000000000000000;
int n;
long long b[100000];




void f() {
	long long lb, ub;
	lb = 1;
	ub = maxv + 1;
	for (int i = n; i > 0;i--) {
		if (i&1) {
			tie(lb, ub) = make_pair(b[i - 1] - ub - 1, b[i - 1] - lb + 1);
		}
		else {
			tie(lb, ub) = make_pair(b[i - 1] + lb, b[i - 1] + ub);
		}
		lb = max(lb, 1LL);
		ub = min(ub, maxv + 1);
		if (lb == ub || ub <= 1 || maxv < lb) {
			cout << -1 << endl;
			return;
		}
	}

	long long x = lb;
	cout << n + 1<< endl;
	cout << x << endl;
	for (int i = 1; i <= n;i++) {
		if (i & 1) {
			x = b[i - 1] - x;
		}
		else {
			x = x - b[i - 1];
		}
		cout << x << endl;
	}
}







int main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n;
	rep(i, n)cin >> b[i];
	f();

	return 0;
}