User Logs

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

namespace UserLogs
{
    class Program
    {
        static void Main(string[] args)
        {
            var dict = new SortedDictionary<string, Dictionary<string, List<string>>>();
            string input = Console.ReadLine();
            Regex pattern = new Regex(@"(?:IP=|)(?<ip>\S+)\s+(?:message=')(?<message>|\S+)(?:')\s+(?:user=)(?<user>\S+)");

            while (input != "end")
            {
                Match match = pattern.Match(input);
                string message = match.Groups[2].Value;
                string user = match.Groups[3].Value;
                string ip = match.Groups[1].Value;

                if (dict.ContainsKey(user))
                {
                    if (dict[user].ContainsKey(ip))
                    {
                        dict[user][ip].Add(message);
                    }
                    else
                    {
                        dict[user].Add(ip, new List<string>() {message} );
                    }
                }
                else
                {
                    dict.Add(user, new Dictionary<string, List<string>>());
                    dict[user].Add(ip, new List<string> { message });
                }

                input = Console.ReadLine(); // new input

            }

            //Print dict
            foreach (var item in dict)
            {
                Console.WriteLine(item.Key + ":");
                Console.WriteLine(String.Join(", ", item.Value.Select(x => x.Key + " => " + x.Value.Count)) + ".");

            }

        }
    }
}