#include <stdio.h>

int Otsuri (int tanka,int kosu,int pay){
return pay - tanka * kosu;
}

void main(void)
{
int otsuri,tanka,kosu,pay;
printf("単価> ");
scanf("%d", &tanka);
printf("購入個数> ");
scanf("%d", &kosu);
printf("支払金額> ");
scanf("%d", &pay);

printf("（実行結果例）\n 単価：%d \n 購入個数：%d \n 支払金額：%d \n----------------- \n おつり：%d 円\n",tanka,kosu,pay,Otsuri(tanka,kosu,pay));
}