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

#define _p(...) (void)printf(__VA_ARGS__)
#define forr(x,arr) for(auto&& x:arr)
#define _overload3(_1,_2,_3,name,...) name
#define _rep2(i,n) _rep3(i,0,n)
#define _rep3(i,a,b) for(int i=int(a);i<int(b);++i)
#define rep(...) _overload3(__VA_ARGS__,_rep3,_rep2,)(__VA_ARGS__)
#define _rrep2(i,n) _rrep3(i,0,n)
#define _rrep3(i,a,b) for(int i=int(b)-1;i>=int(a);i--)
#define rrep(...) _overload3(__VA_ARGS__,_rrep3,_rrep2,)(__VA_ARGS__)
#define all(x) (x).begin(), (x).end()
#define bit(n) (1LL<<(n))
#define sz(x) ((int)(x).size())
#define fst first
#define snd second
using ll=long long;using pii=pair<int,int>;
using vb=vector<bool>;using vs=vector<string>;
using vi=vector<int>;using vvi=vector<vi>;using vvvi=vector<vvi>;
using vl=vector<ll>;using vvl=vector<vl>;using vvvl=vector<vvl>;
using vd=vector<double>;using vvd=vector<vd>;using vvvd=vector<vvd>;
using vpii=vector<pii>;using vvpii=vector<vpii>;using vvvpii=vector<vvpii>;
template<typename T>T read(){T t;cin>>t;return t;}
template<class T,class U>ostream&operator<<(ostream&o,const pair<T,U>&p){o<<'('<<p.fst<<", "<<p.snd<<')';return o;}

void panic() {
  cout << -1 << endl;
  exit(0);
}

void Main() {
  int n = read<int>();
  vector<ll> B(n);
  rep(i, n) B[i] = read<ll>();

  ll inf = 1000000000000000000LL;

  ll lb = 1;
  ll ub = B[0] - 1;

  rep(i, n) {
    if (i%2) {
      lb = lb - B[i];
      ub = ub - B[i];
    }
    else {
      lb = B[i] - lb;
      ub = B[i] - ub;
    }
    if (ub < 1) ub = 1;
    if (lb < 1) lb = 1;
    if (ub > inf) ub = inf;
    if (lb > inf) lb = inf;
    if ((i/2)%2) {
      // v
      if (lb > ub) panic();
    }
    else {
      // ^
      if (lb < ub) panic();
    }
    //cout << "lb: "<<lb << endl;
    //cout << "ub: "<<ub << endl;
  }

  vl ans(n+1);
  ans[n] = lb;
  rrep(i, n) {
    if (i % 2) {
      ans[i] = B[i] + ans[i+1];
    }
    else {
      ans[i] = B[i] - ans[i+1];
    }
    if (ans[i] < 1 || ans[i] > inf) panic();
    //cout << "ans:"; rep(ii,sz(ans)) cout << ' ' << ans[ii]; cout << endl;
  }

  
  cout << n + 1 << endl;
  rep(i, n+1) cout << ans[i] << endl;;
}
int main() { cin.tie(nullptr); ios::sync_with_stdio(false); Main(); return 0; }