P06.Courses (C# Shell App Paste)

//Disclaimer: The creator of 'C# Shell (C# Offline Compiler)' is in no way responsible for the code posted by any user.
using System;
using System.IO;
using System.Linq;
using System.Collections.Generic;

namespace CSharp_Shell
{

    public static class Program
    {
        public static void Main()
        {
           var courses = new Dictionary<string, List<string>>();
           var registeredStudents = 0;
           while (true)
           {
            var input = Console.ReadLine();
            if(input == "end")
            {
                break;
            }
            var items = input.Split(":");
            var courseName = items[0];
            var studentName = items[1];

            if(!courses.ContainsKey(courseName))
            {
                courses[courseName] = new List<string>();
            }
            courses[courseName].Add(studentName);


           }
           foreach(var kvp in courses.OrderByDescending(x=>x.Value.Count).ThenBy(x=>x.Key))
           {
            Console.WriteLine($"{kvp.Key} : {string.Join(string.Empty, kvp.Value.Count)}");
            Console.WriteLine($"-- {string.Join(string.Empty, kvp.Value)}");
           }
        }
    }
}