import java.util.*;
import java.lang.*;

class Main {

    public static void main(String[] args) {
        // Task 6

        Student student1 = new Student("Adam", "Kowalski", 1);
        Student student2 = new Student("Tomek", "Kowalski", 2);
        Student student3 = new Student("Anna", "Kowalski", 3);

        List < Double > studentSubjectGrades1 = new ArrayList < Double > ();
        studentSubjectGrades1.add(4.0);
        studentSubjectGrades1.add(5.0);
        studentSubjectGrades1.add(3.0);
        studentSubjectGrades1.add(4.0);
        studentSubjectGrades1.add(5.0);

        List < Double > studentSubjectGrades2 = new ArrayList < Double > ();
        studentSubjectGrades2.add(4.0);
        studentSubjectGrades2.add(6.0);
        studentSubjectGrades2.add(2.0);
        studentSubjectGrades2.add(4.0);
        studentSubjectGrades2.add(1.0);

        List < Double > studentSubjectGrades3 = new ArrayList < Double > ();
        studentSubjectGrades3.add(4.0);
        studentSubjectGrades3.add(3.0);
        studentSubjectGrades3.add(3.0);
        studentSubjectGrades3.add(2.0);
        studentSubjectGrades3.add(1.0);

        HashMap < Student, List<Double> > newHashMap = new HashMap < Student, List<Double> > ();

        newHashMap.put(student1, studentSubjectGrades1);
        newHashMap.put(student2, studentSubjectGrades2);
        newHashMap.put(student3, studentSubjectGrades3);

        for (Map.Entry <Student, List<Double>> entry: newHashMap.entrySet()) {
            System.out.println("Grades of " + entry.getKey().getStudentID() + " " + entry.getKey().getFirstName() + " " + entry.getKey().getLastName() + " average equals " +
                    avgGrades(entry.getValue()));
        }
    }

    public static double avgGrades(List < Double > averageGradesOfStudents) {
        double average = 0.0;
        for (int i = 0; i < averageGradesOfStudents.size(); i++) {
            average = average + averageGradesOfStudents.get(i);
        }
        return average / averageGradesOfStudents.size();
    }
}


class Student {

    private String firstName;
    private String lastName;
    private Integer studentID;


    public Student(String firstName, String lastName, Integer studentID) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.studentID = studentID;
    }

    @Override
    public boolean equals(Object o) {
        final Student e = (Student) o;
        return this.firstName.equals(e.firstName) && this.lastName.equals(e.lastName) && this.studentID.equals(e.studentID);
    }

    @Override
    public int hashCode() {
        return studentID;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public Integer getStudentID() {
        return studentID;
    }
}