import java.util.*;
import java.io.*;


class Item {
    private String name;
    private double price;
    private int amount;

    public Item(String name, double price){
        setName(name);
        setPrice(price);
        setAmount(1);
    }
    public Item(String name, double price, int amount){
        setName(name);
        setPrice(price);
        setAmount(amount);
    }

    public String getName(){
        return this.name;
    }
    public double getPrice(){
        return this.price;
    }
    public int getAmount(){
        return this.amount;
    }

    public double getTotalPrice(){
        return getPrice()*getAmount();
    }

    public void setName(String name){
        this.name = name;
    }
    public void setPrice(double price){
        if (price >= 0)
            this.price = price;
        else
            throw new IllegalArgumentException("Price cannot be negative");
    }
    public void setAmount(int amount){
        if (amount >= 0)
            this.amount = amount;
        else
            throw new IllegalArgumentException("Amount cannot be negative");
    }

    public String toString(){
        return this.name + "(" + this.amount + ") " + this.price;
    }
}


class Song {
    private String author;
    private String name;
    private int length;
    private String genre;
    private int rating;

    public Song(String author, String name, int length){
        init(author, name, length, "", 0);
    }
    public Song(String author, String name, int length, String genre){
        init(author, name, length, genre, 0);
    }
    public Song(String author, String name, int length, String genre, int rating){
        init(author, name, length, genre, rating);
    }

    private void init(String author, String name, int length, String genre, int rating){
        if (length >= 0){
            this.author = author;
            this.name = name;
            this.length = length;
            this.genre = genre;
            setRating(rating);
        } else {
            throw new IllegalArgumentException("Length cannot be negative");
        }
    }

    public String getAuthor(){
        return author;
    }
    public String getName(){
        return name;
    }
    public int getLength(){
        return length;
    }
    public String getGenre(){
        return genre;
    }
    public int getRating(){
        return rating;
    }


    public void setRating(int rating){
        this.rating = rating;
    }


    public String toString(){
        return author + " - " + name + " (" + length + " sec.), " + genre + ", " + rating + " stars";
    }
}



public class Sandbox {
    public static void main(String args[]) {
        try {
            // input
            Scanner sc = new Scanner(System.in);
            Song[] songs = null;
            while(true){
                try {
                    System.out.println("How many songs?");
                    int size = Integer.parseInt(sc.nextLine());
                    songs = new Song[size];
                    break;
                } catch(Exception e){
                    System.out.print("Error! Please enter how many songs:");
                }
            }

            for(int i = 0; i < songs.length; ){
                try {
                    System.out.print("Enter author: ");
                    String author = sc.nextLine();

                    System.out.print("Enter name: ");
                    String name = sc.nextLine();

                    System.out.print("Enter length: ");
                    int length = Integer.parseInt(sc.nextLine());

                    songs[i] = new Song(author, name, length);

                    System.out.print("Enter rating: ");
                    songs[i].setRating(Integer.parseInt(sc.nextLine()));
                    System.out.println("Song[" + i + "] was read successfully!\n");

                    ++i;

                } catch(Exception e){
                    System.out.println("Error! Please enter data again.");
                }


            }
            sc.close();

            // algorithm
            int totalDuration = 0;
            double averageRating = 0;
            for(int i = 0; i < songs.length; ++i){
                //System.out.println(songs[i]);
                try {
                    totalDuration += songs[i].getLength();
                    averageRating += songs[i].getRating();
                } catch(NullPointerException npe){
                    averageRating += 3;
                }
            }
            averageRating = averageRating/songs.length;

            // output
            System.out.println("Total duration: " + totalDuration + " sec.");
            System.out.println("Average rating: " + averageRating + " stars");


        } catch(Exception e){
            System.out.println(e);
            System.out.println("Unexpected error, sorry!");
        }
    }
}