RoliCoder

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

namespace _04_roliCoder
{
    class Event
    {
        public string  Name { get; set; }
        public List<string> Participants { get; set; }

        public Event(string name,List<string> participants)
        {
            Name = name;
            Participants = participants;
        }
    }
    class roliCoder
    {
        static void Main(string[] args)
        {
            string input = Console.ReadLine();
            string pattern = @"^(?<id>\d+) #(?<name>[\w]*)(?<participants>\s?@\w+)*$";

            Dictionary<int, Event> events = new Dictionary<int, Event>();

            while (input != "Time for Code")
            {
                Match currMatch = Regex.Match(input, pattern);
                if (currMatch.Success)
                {
                    int id = int.Parse(currMatch.Groups["id"].Value);
                    string name = currMatch.Groups["name"].Value;
                    string[] inputTokkens = input.Split(new string[]{ " @", }, StringSplitOptions.RemoveEmptyEntries);
                    List<string> currParticipants = new List<string>();
                    for (int i = 1; i < inputTokkens.Length; i++)
                    {
                        currParticipants.Add(inputTokkens[i]);
                    }

                    if (!events.ContainsKey(id))
                    {
                        events.Add(id, new Event(name, currParticipants));
                    }
                    else
                    {
                        if(events[id].Name == name)
                        {
                            events[id].Participants.AddRange(currParticipants);
                        }
                    }
                }
                input = Console.ReadLine();
            }

            var orderedEvents = events
                .OrderByDescending(ev => ev.Value.Participants.Count)
                .ThenBy(ev => ev.Value.Name);


            foreach (var orderedEvent in orderedEvents)
            {
                string eventName = orderedEvent.Value.Name;

                List<string> guests = orderedEvent.Value.Participants;

                int atendance = orderedEvent.Value.Participants.Distinct().Count();
                Console.WriteLine("{0} - {1}", eventName, atendance);

                List<string> orderedGuests = new List<string>();
                foreach (var guest in guests)
                {
                    if (!orderedGuests.Contains("@" + guest))
                    {
                        orderedGuests.Add("@" + guest);
                    }
                }
                orderedGuests.Sort();

                Console.WriteLine(string.Join("\r\n", orderedGuests));
            }
        }
    }
}