6.Courses

using System;
using System.Linq;
using System.Collections.Generic;
namespace _6.Courses
{
    class Program
    {
        static void Main(string[] args)
        {

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

            while (true)
            {
                var input = Console.ReadLine().Split(" : ").ToArray();
                if (input[0] == "end")
                {
                    break;
                }
                if (!students.ContainsKey(input[0]))
                {
                    students.Add(input[0], new List<string>());
                    students[input[0]].Add(input[1]);
                }
                else
                {
                    students[input[0]].Add(input[1]);
                }
            }

            students = students
                .OrderByDescending(x => x.Value.Count)
                .ThenBy(x => x.Value)
                .ToDictionary(x => x.Key, x => x.Value);



            foreach (var kvp in students)
            {

                Console.WriteLine($"{kvp.Key}: {kvp.Value.Count}");
                var list = kvp.Value;

                foreach (var kvp2 in list)
                {
                    Console.WriteLine($"-- {kvp2}");
                }

            }
        }
    }
}