using System;

namespace ConsoleApp4
{
    class Library {
        Book[] array;
        public Library() {
            array = new Book[0];
        }
        public Library(Book[] arr) {
            array = new Book[arr.Length];
            Array.Copy(arr, array, arr.Length);
        }
        public void AddBook(Book obj) {
            Array.Resize<Book>(ref array, array.Length+1);
            array[array.Length - 1] = obj;
        }
        public Book[] CountBooksWithTheLessAmountOfPages(int n) {
            Book[] arrOfLessBook = new Book[array.Length];
            int count = 0;
            for (int i = 0; i < array.Length; i++) {
                if (array[i].countPages < n) {
                    arrOfLessBook[count] = array[i];
                    count += 1;
                }
            }
            return arrOfLessBook;
        }
        public int Size {
            get {
                return array.Length;
            }
        }
        public void GetInfo() {
            for (int i = 0; i < array.Length; i++) {
                Console.WriteLine($"Количество страниц: {array[i].countPages}, номер секции: {array[i].sectionNumber}");
            }
            Console.WriteLine();
        }
        public Book this[int index] {
            get {
                return array[index];
            }
        }

    }
    class Book {
        int _countPages;
        int _sectionNumber;
        public Book(int _countPages, int _sectionNumber) {
            this._countPages = _countPages;
            this._sectionNumber = _sectionNumber;
        }
        public int countPages {
            get {
                return _countPages;
            }
        }
        public int sectionNumber {
            get {
                return _sectionNumber;
            }
        }
        public void GetBookInfo() {
            Console.WriteLine($"Количество страниц: {_countPages}, номер секции: {_sectionNumber}");
        }

    }
    class Program
    {
        static Random rnd = new Random();

        static void Main()
        {
            do
            {
                int N = rnd.Next(10, 21);
                Library lib = new Library();
                for (int i = 0; i < N; i++)
                {
                    int countPages = rnd.Next(1, 501);
                    int sectionNumber = rnd.Next(5, 11);
                    lib.AddBook(new Book(countPages, sectionNumber));
                }
                lib.GetInfo();
                for (int i = 0; i < N; i++)
                {
                    if (lib[i].countPages < 200)
                    {
                        lib[i].GetBookInfo();
                    }
                }
                Console.WriteLine();
            } while (Console.ReadKey(true).Key != ConsoleKey.Escape);
        }

    }
}