#include<bits/stdc++.h>

using namespace std;

typedef long long int64;
int64 RANGE = 1000000000000000000LL;

int main()
{
  int N;
  int64 B[100000];

  cin >> N;

  int64 xs = 1;
  bool f = false;
  for(int i = 0; i < N; i++) {
    cin >> B[i];
    if(i & 1) xs = xs - B[i];
    else xs = B[i] - xs;
    if(xs <= 0 || xs > RANGE) f = true;
  }

  int64 gs = B[0] - 1;
  bool g = false;
  for(int i = 0; i < N; i++) {
    if(i & 1) xs = xs - B[i];
    else xs = B[i] - xs;
    if(xs <= 0 || xs > RANGE) g = true;
  }

  if(f && g) {
    cout << -1 << endl;
    return (0);
  }

  cout << N + 1 << endl;
  int64 rev = 1;
  if(f) rev = B[0] - 1;
  cout << rev << endl;
  for(int i = 0; i < N; i++) {
    if(i & 1) rev = rev - B[i];
    else rev = B[i] - rev;
    cout << rev << endl;
  }
}