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

const ll inf=1LL<<60;
ll a[100001],b[100000];

int main(void){
	int n;
	cin >> n;

	for(int i=0;i<n;++i) cin >> b[i];
	ll low=1LL,high=inf;

	for(int i=0;i<n;++i){
		ll nlow,nhigh;
		if(i%2==0)
			nlow=max(low-b[i],1LL),nhigh=high-b[i];
		else
			nlow=max(b[i]-high,1LL),nhigh=b[i]-low;
		low=nlow,high=nhigh;
	}

	if(low>high){
		puts("-1");
		return 0;
	}

	a[n]=low;

	for(int i=n-1;i>=0;--i){
		if(i%2)
			a[i]=b[i]+a[i+1];
		else
			a[i]=b[i]-a[i+1];
	}

	cout << n+1 << endl;
	for(int i=0;i<=n;++i) cout << a[i] << endl;

	return 0;
}