public class Main {

    public static void main(String[] args) {

        Person p = new Person("小明", 12);

        Student s = new Student("小红", 20, 99);

        // TODO: 定义PrimaryStudent，从Student继承，新增grade字段:

        Student ps = new PrimaryStudent("小军", 9, 100, 5);

        System.out.println(ps.getScore());

        System.out.println(((PrimaryStudent)ps).getGrade());

    }

}

class Person {

    protected String name;

    protected int age;

    public Person(String name, int age) {

        this.name = name;

        this.age = age;

    }

    public String getName() { return name; }

    public void setName(String name) { this.name = name; }

    public int getAge() { return age; }

    public void setAge(int age) { this.age = age; }

}

class Student extends Person {

    protected int score;

    public Student(String name, int age, int score) {

        super(name, age);

        this.score = score;

    }

    public int getScore() { return score; }

}

class PrimaryStudent extends Student {

    protected int grade;

    public PrimaryStudent(String name, int age, int score, int grade) {

        super(name, age, score);

        this.grade = grade;

    }

    public int getGrade() {

        return grade;

    }

}