#include <cstdio>
#include <algorithm>
#include <iostream>
#include <vector>
#define ll long long int
using namespace std;

int main(void){

  ll n;
  ll a[111111],b[111111];
  int i;
  cin>>n;
  for(i=1;i<=n;i++){
    cin>>b[i];
  }

  a[1]=1;
  for(i=2;i<=n+1;i++){
    a[i]=(i%2)?(a[i-1]-b[i-1]):(b[i-1]-a[i-1]);
    if(a[i]<=0){
      cout<<"-1\n";
      return 0;
    }
  }
  cout<<n+1<<endl;
  for(i=1;i<=n+1;i++){
    cout<<a[i]<<endl;
  }

  return 0;
}