ForceBook

using System;
using System.Collections.Generic;
using System.Linq;

namespace _04Problem_MyExam
{
    class Program
    {
        static void Main(string[] args)
        {
            string input = string.Empty;

            SortedDictionary<string, List<string>> forceSides = new SortedDictionary<string, List<string>>();

            while ((input = Console.ReadLine()) != "Lumpawaroo")
            {
                string[] splitInput = input.Split(new string[] { " -> ", " | " }, StringSplitOptions.RemoveEmptyEntries);

                string side = string.Empty;
                string user = string.Empty;
                string oldSide = string.Empty;

                if (input.Contains(" -> "))
                {
                    user = splitInput[0];
                    side = splitInput[1];

                    if (forceSides.ContainsKey(side) == false)
                    {
                        forceSides.Add(side, new List<string>());
                        forceSides[side].Add(user);
                    }
                    else
                    {
                        if (forceSides[side].Contains(user))
                        {
                            forceSides[side].Remove(user);
                        }

                        forceSides[side].Add(user);
                    }

                    Console.WriteLine($"{user} joins the {side} side!");
                }
                else if (input.Contains(" | "))
                {
                    user = splitInput[1];
                    side = splitInput[0];

                    if (forceSides.ContainsKey(side) == false)
                    {
                        forceSides.Add(side, new List<string>());
                    }

                    if (forceSides[side].Contains(user) == false)
                    {
                        forceSides[side].Add(user);
                    }
                }
            }

            foreach (var sideAndUsers in forceSides.OrderByDescending(x => x.Value.Count()))
            {
                Console.WriteLine($"Side: {sideAndUsers.Key}, Members: {sideAndUsers.Value.Count}");

                foreach (var user in sideAndUsers.Value.OrderBy(x => x))
                {
                    Console.WriteLine($"! {user}");
                }
            }
        }
    }
}