06.Courses

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

namespace Courses
{
    public class Course
    {
        public string Courses { get; set; }
        public int People { get; set; }
        public List<string> Students { get; set; }

        public Course(string courses)
        {
            this.Courses = courses;
            this.People = 1;
            this.Students = new List<string>();

        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            List<Course> CoursesAndStudents = new List<Course>();
            while (true)
            {

                List<string> information = Console.ReadLine()
                    .Split(new[] { " : " }, StringSplitOptions.RemoveEmptyEntries)
                    .ToList();
                string courses = information[0];

                if (courses == "end")
                {
                    break;
                }
                string person = information[1];
                bool isExist = CoursesAndStudents
                    .Any(x => x.Courses.Contains(courses));
                Course addingStudents = new Course(courses);

                if (!isExist)
                {
                    CoursesAndStudents.Add(addingStudents);
                    int index = CoursesAndStudents.FindIndex(x => x.Courses == courses);
                    CoursesAndStudents[index].Students.Add(person);

                }
                else
                {
                    int index = CoursesAndStudents.FindIndex(x => x.Courses == courses);
                    CoursesAndStudents[index].Students.Add(person);
                    CoursesAndStudents[index].People++;
                }


            }
            var SortedCoursesAndStudents = CoursesAndStudents
               .OrderByDescending(x => x.People);




            foreach (var kvp in SortedCoursesAndStudents)
            {
                Console.WriteLine($"{kvp.Courses}: {kvp.People}");

                foreach (var student in kvp.Students.OrderBy(x => x))
                {
                    Console.WriteLine($"-- {student}");
                }
            }
        }

    }
}