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 }