public class Test{  //Person,Student類的定義同示例7-6
	public static  void main(String args[]){
	  Student m = new Student();
	  m.school = "pku"; 	//合法
	  Person e = new Student(); 
	  e.school = "pku";	//非法
	}
}


class Person {
	protected String name;
	protected int age;
	public String getInfo() {
	   	return "Name: "+ name + "\n" +"age: "+ age;
	}
}

class Student extends Person {
	protected String school;
	public String getInfo() {
  	   	return  "name: "+ name + "\nage: "+ age 
	          + "\nschool: "+ school;
	}
}