>271
#include <stdio.h>
int main(void){
int price, num, amount;
printf("商品単価：");
scanf("%d", &price);
printf("購入数量：");
scanf("%d", &num);
if(num>=500) amount = price * num * 0.7;
else if(num>=100) amount = price * num * 0.75;
else if(num>=10) amount = price * num * 0.8;
else amount = price * num;
printf("購入金額：%d円", amount);
return 0;}