当你在超市买了price元商品，并且付给了售货员amount元（amount>=price）时，售货员应该找你多少元钱？
Scanner in = new Scanner(System.in);
int price=0;
int amount=100;
System.out.print("请输入票面:");
amount = in.nextInt();
System.out.print("请输入金额:");
price = in.nextInt();
System.out.println(amount+"-"+price+"="+(amount-price));