java的加油优惠问题，请解答一下！

public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.print("请输入加油量:");
        int yl = sc.nextInt();
        System.out.print("汽油种类（90号汽油/93号汽油/97号汽油/0号柴油）:");
        String lx = sc.next();
        System.out.print("服务等级(自助加油/协助加油):");
        String fw = sc.next();
        
        double s =0;
        if(lx.equals("90号汽油"))
            s = yl * 6.8;
        else if(lx.equals("93号汽油"))
            s = yl * 6.42;
        else if(lx.equals("97号汽油"))
            s = yl * 7.02;
        else if(lx.equals("0号柴油"))
            s = yl * 5.75;
        else{
            System.out.println("类型输入错误");
            return ;
        }
        
        if(fw.equals("自助加油"))
            s = s*0.9;
        else if(fw.equals("协助加油"))
            s = s*0.95;
        else{
            System.out.println("服务等级输入错误");
            return;
        }
        
        System.out.println("应付金额="+s);
    }