using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        var d = ri();
        var a = new int[100001];
        a = ria();

        for(int i = d; i >= 3; i--)
            a[i - 2] += a[i];

        if (a[2] == 0)
        {
            if (a[1] == 0)
            {
                Console.WriteLine(0);
                if (a[0] == 0)
                    Console.WriteLine(0);
                else
                    Console.WriteLine(a[0]);
            }
            else
            {
                Console.WriteLine(1);
                Console.WriteLine(a[0] + " " + a[1]);
            }
        }
        else
        {
            Console.WriteLine(2);
            Console.WriteLine(a[0] + " " + a[1] + " " + a[2]);
        }
    }

    #region Scan
    static int ri() { return int.Parse(Console.ReadLine().Trim()); }
    static long rl() { return long.Parse(Console.ReadLine().Trim()); }
    static double rd() { return double.Parse(Console.ReadLine().Trim()); }
    static string rs() { return Console.ReadLine().Trim(); }
    static int[] ria() { return Console.ReadLine().Trim().Split().Select(int.Parse).ToArray(); }
    static long[] rla() { return Console.ReadLine().Trim().Split().Select(long.Parse).ToArray(); }
    static double[] rda() { return Console.ReadLine().Trim().Split().Select(double.Parse).ToArray(); }
    static string[] rsa() { return Console.ReadLine().Trim().Split(); }
    static void mul(out int a, out int b) { var arr = ria(); a = arr[0]; b = arr[1]; }
    static void mul(out int a, out int b, out int c) { var arr = ria(); a = arr[0]; b = arr[1]; c = arr[2]; }
    static void mul(out int a, out int b, out int c, out int d) { var arr = ria(); a = arr[0]; b = arr[1]; c = arr[2]; d = arr[3]; }
    static void mul(out long a, out long b) { var arr = rla(); a = arr[0]; b = arr[1]; }
    static void mul(out long a, out long b, out long c) { var arr = rla(); a = arr[0]; b = arr[1]; c = arr[2]; }
    static void mul(out long a, out long b, out long c, out long d) { var arr = rla(); a = arr[0]; b = arr[1]; c = arr[2]; d = arr[3]; }
    #endregion
    #region Math
    const int mod = 1000000007;
    static bool isprime(long n){ if (n < 2) return false; for (long i = 2; i * i <= n; i++) if (n % i == 0) return false; return true; }
    static long gcd(long a, long b) { return a == 0 ? b : gcd(b % a, a); }
    static long lcm(long a, long b) { return a * b / gcd(a, b); }
    #endregion
}