定义一个Document类，包含成员变量name,从Document派生出Book类，增加PageCount变量。编写主函数

class Document
{
 private String name;
 public Document(String name){
  this.name = name;
 }
 public String getName(){
  return name;
 }
 public void setName(String name){
  this.name = name;
 }
}

class Book extends Document
{
 private int PageCount;
 public Book(String name,int PageCount){
  super (name);
  this.PageCount = PageCount;
 }
 public int getPage(){
  return PageCount;
 }
 public void setPage(){
  this.PageCount = PageCount;
 }
}

public class Test