#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<int> vi;
typedef vector<ll> vl;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

typedef int _loop_int;
#define REP(i,n) for(_loop_int i=0;i<(_loop_int)(n);++i)
#define FOR(i,a,b) for(_loop_int i=(_loop_int)(a);i<(_loop_int)(b);++i)
#define FORR(i,a,b) for(_loop_int i=(_loop_int)(b)-1;i>=(_loop_int)(a);--i)

#define DEBUG(x) cout<<#x<<": "<<x<<endl
#define DEBUG_VEC(v) cout<<#v<<":";REP(i,v.size())cout<<" "<<v[i];cout<<endl
#define ALL(a) (a).begin(),(a).end()

#define CHMIN(a,b) a=min((a),(b))
#define CHMAX(a,b) a=max((a),(b))

// mod
const ll MOD = 1000000007ll;
#define FIX(a) ((a)%MOD+MOD)%MOD

// floating
typedef double Real;
const Real EPS = 1e-11;
#define EQ0(x) (abs(x)<EPS)
#define EQ(a,b) (abs(a-b)<EPS)
typedef complex<Real> P;

int n;
ll b[125252];
ll a[125252];

int main(){
  scanf("%d",&n);
  REP(i,n)scanf("%lld",b+i);
  a[0] = 1;
  ll minusmin = 2e18, plusmin = 2e18;
  REP(i,n){
    if(i%2==0){
      a[i+1] = b[i] - a[i];
    }else{
      a[i+1] = a[i] - b[i];
    }
    if(i&2){
      // plus
      CHMIN(plusmin,a[i+1]);
    }else{
      // minus
      CHMIN(minusmin,a[i+1]);
    }
  }
  if(plusmin <= 0)a[0] = 2 - plusmin;
  ll check = a[0];
  REP(i,n){
    if(i%2==0){
      a[i+1] = b[i] - a[i];
    }else{
      a[i+1] = a[i] - b[i];
    }
    CHMIN(check,a[i+1]);
  }
  if(check<=0){
    puts("-1");
  }else{
    printf("%d\n",n+1);
    REP(i,n+1)printf("%lld\n",a[i]);
  }
  return 0;
}