Roli the coder

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

namespace _04_RoliTheCoder
{
    class RoliTheCoder
    {
        static void Main(string[] args)
        {
            var input = Console.ReadLine();
            var idEventName = new Dictionary<int, string>();
            var eventNameParticipants = new Dictionary<string, List<string>>();
            var regex = @"(?<id>\d+)\s+#(?<eventName>[\w\d]+)(\s+(?:@\w+\s*)+)?";
            var namePattern = @"@[a-zA-Z0-9'-]+";

            while (input != "Time for Code")
            {
                var matchedInput = Regex.Match(input, regex);

                if (matchedInput.Success)
                {
                    var id = int.Parse(matchedInput.Groups["id"].Value);
                    var eventName = matchedInput.Groups["eventName"].Value;

                    var matchedNames = Regex.Matches(input, namePattern)
                        .Cast<Match>()
                        .Select(a => a.Value)
                        .Where(a => a != "")
                        .ToArray();

                    if (!idEventName.ContainsKey(id))
                    {
                        idEventName[id] = string.Empty;
                        idEventName[id] = eventName;
                        eventNameParticipants[eventName] = new List<string>();
                    }

                    if (idEventName.ContainsKey(id) && !idEventName.ContainsValue(eventName))
                    {
                        input = Console.ReadLine();
                        continue;
                    }

                    foreach (var name in matchedNames.Where(a => a != string.Empty))
                    {
                        eventNameParticipants[eventName].Add(name);
                    }

                    eventNameParticipants[eventName] = eventNameParticipants[eventName].Distinct().ToList();
                }

                input = Console.ReadLine();
            }

            foreach (var kvp in eventNameParticipants.OrderByDescending(p => p.Value.Count))
            {
                Console.WriteLine($"{kvp.Key} - {kvp.Value.Count}");

                foreach (var name in kvp.Value.OrderBy(n => n))
                {
                    Console.WriteLine(name);
                }
            }


        }
    }
}