10

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

namespace ExamPreparation
{
    public sealed class Group
    {
        public Group(Town town)
        {
            this.Town = town;
            this.Students = new List<Student>();
        }

        public Town Town { get; private set; }

        public List<Student> Students { get; set; }

        public override string ToString()
        {
            return $"{this.Town.Name} => {string.Join(", ", this.Students)}";
        }
    }

    public sealed class Town
    {
        public Town(string name, int seatsCount)
        {
            this.Name = name;
            this.SeatsCount = seatsCount;
            this.Students = new List<Student>();
        }

        public string Name { get; private set; }

        public int SeatsCount { get; private set; }

        public List<Student> Students { get; set; }
    }

    public sealed class Student
    {
        public Student(string name, string email, DateTime registrationDate)
        {
            this.Name = name;
            this.Email = email;
            this.RegistrationDate = registrationDate;
        }

        public string Name { get; private set; }

        public string Email { get; private set; }

        public DateTime RegistrationDate { get; private set; }

        public override string ToString()
        {
            return this.Email;
        }
    }

    public sealed class Preparation
    {
        public static void Main()
        {
            string input = Console.ReadLine();
            List<Town> towns = new List<Town>();

            while (input != "End")
            {
                if (input.Contains("=>"))
                {
                    string[] townTokens = input.Split(new[] { '=', '>'}, StringSplitOptions.RemoveEmptyEntries);
                    string townName = townTokens[0].Trim();

                    string[] seatTokens = townTokens[1].Split(new[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
                    int seatsCount = int.Parse(seatTokens[0]);
                    Town town = new Town(townName, seatsCount);
                    towns.Add(town);
                }
                else
                {
                    string[] tokens = input.Split(new[] { '|' }, StringSplitOptions.RemoveEmptyEntries);
                    string studentName = tokens[0].Trim();
                    string email = tokens[1].Trim();
                    DateTime registrationDate = DateTime.ParseExact(tokens[2].Trim(), "d-MMM-yyyy", CultureInfo.InvariantCulture);
                    Student student = new Student(studentName, email, registrationDate);

                    towns[towns.Count - 1].Students.Add(student);
                }

                input = Console.ReadLine();
            }

            List<Group> groups = DistributeStudentsIntoGroups(towns);
            Console.WriteLine($"Created {groups.Count} groups in {towns.Count} towns:");

            groups.ForEach(g => Console.WriteLine(g));
        }

        private static List<Group> DistributeStudentsIntoGroups(List<Town> towns)
        {
            List<Group> groups = new List<Group>();

            foreach (var town in towns.OrderBy(t => t.Name))
            {
                IEnumerable<Student> students = town.Students
                        .OrderBy(s => s.RegistrationDate)
                        .ThenBy(s => s.Name)
                        .ThenBy(s => s.Email);

                while (students.Any())
                {
                    Group group = new Group(town);
                    group.Students = students.Take(group.Town.SeatsCount).ToList();
                    students = students.Skip(town.SeatsCount);
                    groups.Add(group);
                }
            }

            return groups;
        }
    }
}