//Using SortedDictionary<K,T> print on the console the specialties in an

//alphabetical order and for each of them print the names of the students,

//firstly sorted by family name and secondly – by first name

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.IO;

​

​

public class StudentsExtraction

{

    class Student

    {

        private string fistName;

        private string lastName;

        public Student(string fistName, string lastName)

        {

            this.fistName = fistName;

            this.lastName = lastName;

        }

​

        public string FistName

        {

            get

            {

                return this.fistName;

            }

​

            set

            {

                this.fistName = value;

            }

        }

​

        public string LastName

        {

            get

            {

                return this.lastName;

            }

​

            set

            {

                this.lastName = value;

            }

        }

    }

​

    public static void Main(string[] args)

    {

        StreamReader reader = new StreamReader(@"C:\Users\ntb\Desktop\test.txt");

        SortedDictionary<string, List<Student>> students = new SortedDictionary<string, List<Student>>();

        using (reader)

        {

            string line = reader.ReadLine();

            while (line != null)

            {

                string[] studentInfo = line.Split(new char[]{'|', ' '}, StringSplitOptions.RemoveEmptyEntries);

                Student newStudent = new Student(studentInfo[0], studentInfo[1]);

                if (!students.ContainsKey(studentInfo[2]))

                {

                    students.Add(studentInfo[2], new List<Student>()

                    {newStudent});

                    line = reader.ReadLine();

                    continue;

                }

​

                students[studentInfo[2]].Add(newStudent);

                line = reader.ReadLine();

            }

        }

​

        var subjects = students.Keys;

        StringBuilder rezult = new StringBuilder();

        foreach (var studentsInSubject in subjects)

        {

            List<Student> listOfStudents = students[studentsInSubject];

            var sortedStudets = listOfStudents.OrderBy(x => x.LastName);

            rezult.Append(studentsInSubject + ":");

            foreach (var student in sortedStudets)

            {

                rezult.Append(" " + student.FistName + " " + student.LastName + ",");

            }

​

            rezult.Remove(rezult.Length - 1, 1);

            rezult.AppendLine();

        }

​

        rezult.Remove(rezult.Length - 1, 1);

        Console.WriteLine(rezult);

    }

}