哈利波特书价问题

package 哈利波特书;

public class aa {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int a;
		double b,c;
		System.out.println("本数    最低价   ");
		for(a=1;a<22;a++)
		{
			if(a%5==0)
			{
				b=0;
			}
			else if(a%5==1)
			{
				b=8*1;
			}
			else if(a%5==2)
			{
				b=8*2*0.95;
			}
			else if(a%5==3)
			{
				b=8*3*0.9;
			}
			else
			{
				b=8*4*0.8;
			}
			
			
			if(a%5!=3||a<5)
			{
				c=a/5*30+b;
			}
			else
			{
				c=(a/5-1)*30+2*8*4*0.8;
			}
				System.out.print(a+"   ");
				System.out.println(c);
		}
	}

}