function solve() {
    class LibraryCollection {
        constructor(capacity) {
            this.capacity = capacity;
            this.books = [];



        }
        addBook(bookName, bookAuthor) {
            console.log(books);
            if (this.books.length == this.capacity) {
                return "Not enough space in the collection.";
            }
            else {
                let newbook =
                {
                    bookName: bookName,
                    bookAuthor: bookAuthor,
                    Payed: false
                }
                this.books.push(newbook);
                return `The ${bookName}, with an author ${bookAuthor}, collect.`
            }
        };


        payBook(bookName) {
            let bookFound = false;
            let bookID = 0;
            for (let i = 0; i < this.books.length; i++) {
                if (this.books[i].bookName = bookName) {
                    bookFound = true;
                    bookID = i;
                    break;
                }
                if (bookFound) {
                    if (this.books[bookID].Payed == false) {
                        this.books[bookID].Payed = true;
                        return `${this.books[bookID].bookName} has been successfully paid.`;
                    }
                    else {
                        throw `${this.books[bookID].bookName} has been successfully paid.`;
                    }
                }
                else {
                    throw `${this.books[bookID].bookName} is not in the collection.`;
                }
            }
        }
        removeBook(bookName) {
            let bookFound = false;
            let bookID = 0;
            for (let i = 0; i < this.books.length; i++) {
                if (this.books[i].bookName = bookName) {
                    bookFound = true;
                    bookID = i;
                    break;
                }
                if (bookFound) {
                    if (this.books[bookID].Payed == false) {
                        // error
                        throw `${this.books[bookID].bookName} need to be paid before removing from the collection.`;
                    }
                    else {
                        // remove
                        this.books.splice(bookID, 1);
                    }
                }
                else {
                    throw "The book, you're looking for, is not found."
                }
            }
        }
        getStatistics(bookAuthor) {


            if (arguments.length == 0) {
                return this.books;
            }
            else {
                let authorFound = false;
                for (book of this.books) {
                    if (book.bookAuthor == bookAuthor) {
                        authorFound = true; break;
                    }
                }
                if (authorFound) {
                    let emptySlots = this.capacity - this.books.length;
                    if (emptySlots > -1) {
                        console.log(`The book collection has ${emptySlots} empty spots left.`)
                    }

                    this.books.sort(function (a = a.bookName, b = b.bookName) {
                        return a - b;
                    });
                    let Allbooks = '';
                    for (book of this.books) {
                        if (book.Payed == true) {
                            Allbooks += (`${book.bookName} == ${book.bookAuthor} - Has Paid.`)
                        }
                        else {
                            Allbooks += (`${book.bookName} == ${book.bookAuthor} - Not Paid.`)
                        }
                    }
                    return Allbooks;
                }
                else {
                    throw `${bookAuthor} is not in the collection.`;
                }

            }
        }
    }
     //TEST - MUST REMOVE BEFORE PUTTING IN JUDGE
     //----------------------------------------------------
     const library = new LibraryCollection(2)
console.log(library.addBook('In Search of Lost Time', 'Marcel Proust'));
console.log(library.addBook('Don Quixote', 'Miguel de Cervantes'));
console.log(library.addBook('Ulysses', 'James Joyce'));
 //----------------------------------------------------
}
 //TEST - MUST REMOVE BEFORE PUTTING IN JUDGE
solve();
 //----------------------------------------------------