inbox manager

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

namespace _02._Boss_Rush
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] command = Console.ReadLine().Split("->");

            Dictionary<string, List<string>> message = new Dictionary<string, List<string>>();

            while (command[0] != "Statistics")
            {
                if (command[0] == "Add")
                {
                    if (message.ContainsKey(command[1]))
                    {
                        Console.WriteLine($"{command[1]} is already registered");
                    }
                    else
                    {
                        message[command[1]] = new List<string>();
                    }
                }
                if (command[0] == "Send")
                {
                    message[command[1]].Add(command[2]);
                }
                if (command[0] == "Delete")
                {
                    if (message.ContainsKey(command[1]))
                    {
                        message.Remove(command[1]);
                    }
                    else
                    {
                        Console.WriteLine($"{command[1]} not found!");
                    }
                }

                command = Console.ReadLine().Split("->");
            }

            Console.WriteLine($"Users count: {message.Count}");

            foreach (var item in message.OrderByDescending(x => x.Value.Count).ThenBy(x => x.Key))
            {
                Console.WriteLine($"{item.Key}");
                foreach (var kvp in item.Value)
                {
                    Console.WriteLine($"- {kvp}");
                }
            }
        }
    }
}