APP5 Hidden Meta-game Solution

CodeSubmitter.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;

namespace APP5
{
    class Program
    {
        static void Main(string[] args)
        {
            Parallel.ForEach(Items, code =>
            {
                //Console.WriteLine(code);
                SubmitAnswer(code);
            });
            
            Console.WriteLine("done");
            Console.ReadLine();
        }
        
        static List<string> c
        {
            get
            {
                var l = new List<string>();
                l.AddRange(Enumerable.Range(65, 26).Select(o => Char.ConvertFromUtf32(o).ToString()));
                l.AddRange(Enumerable.Range(0, 10).Select(o => o.ToString()));
                return l;
            }
        }
        
        static IEnumerable<string> Items
        {
            get
            {
                int count = c.Count;
                for (int a = 0; a < count; a++)
                    for (int b = 0; b < count; b++)
                        for (int z = 0; z < count; z++)
                            for (int d = 0; d < count; d++)
                                for (int e = 0; e < count; e++)
                                    for (int f = 0; f < count; f++)
                                        yield return c[a] + c[b] + c[z] + c[d] + c[e] + c[f];
            }
        }
        
        static void SubmitAnswer(string code)
        {
            string parameters = "csrfmiddlewaretoken=REDACTED&code=" + code;
            string reply;
            using (var wc = new App5WebClient())
            {
                wc.Headers[HttpRequestHeader.ContentType] = "application/x-www-form-urlencoded";
                wc.Encoding = Encoding.UTF8;
                reply = wc.UploadString("http://app5.jdabbs.com/solve/", parameters);
            }
            reply = null;
        }
    }
    
    class App5WebClient : WebClient
    {
        protected override WebRequest GetWebRequest(Uri address)
        {
            var request = base.GetWebRequest(address);
            
            var cookies = new CookieContainer();
            cookies.Add(new Cookie("sessionid", "REDACTED", "/", "app5.jdabbs.com"));
            cookies.Add(new Cookie("csrftoken", "REDACTED", "/", "app5.jdabbs.com"));
            
            if (request is HttpWebRequest)
            {
                (request as HttpWebRequest).CookieContainer = cookies;
            }
            
            return request;
        }
    }
}