using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Globalization;
using static System.Console;
using Pair = System.Collections.Generic.KeyValuePair<int, int>;

class Program
{
    static void Main()
    {
        var sw = new StreamWriter(OpenStandardOutput()) { AutoFlush = false };
        SetOut(sw);
        new Program().solve();
        Out.Flush();
    }
    Scanner cin = new Scanner();
    readonly int[] dd = { 0, 1, 0, -1, 0 };
    readonly int mod = 1000000007;
    readonly string alfa = "abcdefghijklmnopqrstuvwxyz";

    int n;
    bool flag = true;
    void solve()
    {
        n = cin.nextint;
        var b = new long[n];
        for (int i = 0; i < n; i++)
        {
            b[i] = cin.nextlong;
        }
        if (b.Min() == 1) flag = false;


        var a = new long[n + 1];
        a[0] = 1;
        for (int i = 1; i < n + 1; i++)
        {
            if (i % 2 == 1) a[i] = b[i - 1] - a[i - 1];
            else a[i] = a[i - 1] - b[i - 1];

            if(a[i] <= -1*(long)Math.Pow(10,18))
            {
                flag = false;
            }
        }
        
        var min = a.Min();
        var max = a.Max();


        if (flag)
        {
            WriteLine(n + 1);
            foreach (var v in a)
            {
                WriteLine(v);
            }
        }
        else
        {
            WriteLine(-1);
        }
       
    }

}

class Scanner
{
    string[] s; int i;
    char[] cs = new char[] { ' ' };
    public Scanner() { s = new string[0]; i = 0; }
    public string[] scan { get { return ReadLine().Split(); } }
    public int[] scanint { get { return Array.ConvertAll(scan, int.Parse); } }
    public long[] scanlong { get { return Array.ConvertAll(scan, long.Parse); } }
    public double[] scandouble { get { return Array.ConvertAll(scan, double.Parse); } }
    public string next
    {
        get
        {
            if (i < s.Length) return s[i++];
            string st = ReadLine();
            while (st == "") st = ReadLine();
            s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
            i = 0;
            return next;
        }
    }
    public int nextint { get { return int.Parse(next); } }
    public long nextlong { get { return long.Parse(next); } }
    public double nextdouble { get { return double.Parse(next); } }
}