MentorGroup

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

namespace MentorGroup
{
    class Student
    {
        public string Name { get; set; }
        public List<DateTime> Attendance { get; set; }
        public List<string> Comments { get; set; }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var students = new Dictionary<string, Student>();
            string input = Console.ReadLine();

            while (input != "end of dates")
            {
                string[] nameAndDates = input.Split(' ');
                string name = nameAndDates[0];
                List<string> dates = new List<string>();
                dates = nameAndDates[1].Split(',').ToList();
                Student student = new Student();
                student.Name = name;
                student.Attendance = new List<DateTime>();
                student.Comments = new List<string>();
                foreach (var data in dates)
                {
                    student.Attendance.Add(DateTime.ParseExact(data, "dd/MM/yyyy", CultureInfo.InvariantCulture));
                }
                if (students.ContainsKey(name) == false)
                {
                    students.Add(name, student);
                }
                else
                {
                    students[name].Attendance.AddRange(student.Attendance);
                }

                input = Console.ReadLine();
            }

            input = Console.ReadLine();

            while (input != "end of comments")
            {
                var namesAndComments = input.Split('-');
                string currentName = namesAndComments[0];
                string comment = namesAndComments[1];
                if (students.ContainsKey(currentName))
                {
                    students[currentName].Comments.Add(comment);
                }
                input = Console.ReadLine();
            }


            foreach (var student in students.OrderBy(x => x))
            {
                Console.WriteLine(student.Key);
                Console.WriteLine("Comments:");
                foreach (var comment in student.Value.Comments)
                {
                    Console.WriteLine($"- {comment}");
                }
                Console.WriteLine("Dates attended:");
                foreach (var date in student.Value.Attendance.OrderBy(x => x))
                {
                    Console.WriteLine($"-- {date.Day}/{date.Month}/{date.Year}");
                }
            }

        }

    }
}