飞机票打折程序怎么写?

import java.util.Scanner;

public class BuyFeiJiPiao{

public void buyNum(int num){
if(0< num && num <= 10){
System.out.println("价格：￥"+(1000*num*0.9));
}else if(10 < num && num <= 20){
System.out.println("价格：￥"+(1000*num*0.8));
}else{
System.out.println("价格：￥"+(1000*num*0.7));
}
}

public void buyDaZe(int num){
switch (num) {
case 9:
System.out.println("打折数量范围：1 - 10");
break;
case 8:
System.out.println("打折数量范围：11 - 20");
break;
case 7:
System.out.println("打折数量大于20张");
break;

default:
break;
}
}

public static void main(String[] args) {
BuyFeiJiPiao b = new BuyFeiJiPiao();
Scanner sc = new Scanner(System.in);
System.out.print("请输入购买的票数：");
String num = sc.next();
b.buyNum(Integer.parseInt(num));
System.out.print("请输入折扣：");
String n = sc.next();
b.buyDaZe(Integer.parseInt(n));
}

}