#include<stdio.h>
void main()
{
	int num;
	double money,dcount,result; 
	printf("\n 請輸入購買數量：");
	scanf("%d",&num);
	printf("\n 請輸入該商品的價格：");
	scanf("%lf",&money);

	if(num>5)
		dcount=0; 
	else if((num>=5)&&(num<10))
		dcount=0.01;
	else if((num>=10)&&(num<20))
		dcount=0.02;
	else if((num>=20)&&(num<30))
		dcount=0.04;
	else
		dcount=0.06;
    
	result=money*num-money*num*dcount;
	printf("應付金額為：%7.2f",result);
}