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

#define fi first
#define se second
#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define each(itr,v) for(auto itr:v)
#define pb(s) push_back(s)
#define mp(a,b) make_pair(a,b)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define maxch(x,y) x=max(x,y)
#define minch(x,y) x=min(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt(x) bitset<32>(x).count()

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> P;
typedef pair<P, int> PPI;
typedef pair<ll, ll> PL;
typedef pair<P, ll> PPL;

#define INF INT_MAX/3

#define MAX_N 1000

ll b[111111];
ll a[111111];
int n;

int main(){
	cin.sync_with_stdio(false);
	cin>>n;
	rep(i,n)cin>>b[i];
	a[0]=1;
	repl(i,1,n+1){
		if(i%2==1){
			a[i]=b[i-1]-a[i-1];
		}else{
			a[i]=a[i-1]-b[i-1];
		}
	}
	rep(i,n+1){
		if(a[i]<=0){
			cout<<-1<<endl;
			return 0;
		}
	}
	cout<<n+1<<endl;
	rep(i,n+1)cout<<a[i]<<endl;
	return 0;
}