How much did the businessman lose
Time Limit:
1000MS |
|
Memory Limit:
65536K |
Total Submissions:
7880 |
|
Accepted:
5272 |
Description
Businessmen,
of course, can make much money. However, sometimes, they would lose
money in trading. For example, Jame, a businessman, brought in some
goods each cost him 40 yuan and he decided to sell at the price of 70
yuan. Then a customer came to buy one, gave Jame 100 yuan, and of course
got back 30 yuan. You may said, "Jame earned 30 yuan." But
unfortunately, Jame found the 100 yuan from the customer was fake. What a
poor man! In this case Jame lost 70 yuan (40 (the goods price) + 30
(the money paid back to the customer)).
Now your task is to calculate how much Jame would lose in this kind
of trade. Of course in this case, sometimes Jame may still earn.
Input
The
input consists of several instances. Each instance contains four
integers N, M, P and C, which are all in the range [0, 50000], separated
by a single space.
N is the cost price of Jame good.
M is the sell price.
P is the total fake money the customer gave Jame.
C is how much Jame paid back to the customer.
Here N < M. And P may be less than M, as customer may pay with some fake money and some true money.
The input is terminated by a line containing 4 zeros.
Output
For one
instance, output one line contains exactly one integer, which tells how
much Jame lost in the trade. If Jame still earned, just output a
negative integer, the absolute value of which tells the money Jame
earned.
Sample Input
40 70 100 30
40 70 50 20
14604 32391 3902 153
0 0 0 0
Sample Output
70
20
-13885
Source