public class Main {
    public static void main(String[] args) {
    Person p = new Person("小明", 12);
    Student s = new Student("小红", 20, 99);
    // 定义PramaryStudent, 从Student继承, 新增grade字段:
    Student ps = new PrimaryStudent("小军", 9, 100, 5);
    System.out.println(ps.getScore());
    }
}
class Person {
    protected String name;
    protected int age;
 
public Person(String name, int age) {
    this.name = name;
    this.age = age;
}
 
public void setName(String name) {
    this.name = name;
}
public String getName() {
   return this.name;
}
public void setAge(int age) {
    this.age = age;
}
public int getAge() {
    return this.age;
    }
}
class Student extends Person {
    protected int score;
    public Student(String name, int age, int score) {
    super(name, age);
    this.score = score;
} 
public void setScore(int score) {
   this.score = score;
}
public int getScore() {
    return this.score;
}
}
class PrimaryStudent extends Student {
    private int grade;
    public PrimaryStudent(String name, int age, int score, int grade) {
    super(name, age, score);
    this.grade = grade;
}
public int getGrade() {
    return this.grade;
}
public void setGrade(int grade) {
    this.grade = grade;
    }
}