Problem:
Score : 100 points

Problem Statement

You went shopping to buy cakes and donuts with X yen (the currency of Japan).

First, you bought one cake for A yen at a cake shop.
Then, you bought as many donuts as possible for B yen each, at a donut shop.

How much do you have left after shopping?

Constraints

1 \leq A, B \leq 1 000

A + B \leq X \leq 10 000

X, A and B are integers.

Input

Input is given from Standard Input in the following format:

X
A
B

Output

Print the amount you have left after shopping.

Sample Input 1

1234
150
100

Sample Output 1

84

You have 1234 - 150 = 1084 yen left after buying a cake.
With this amount, you can buy 10 donuts, after which you have 84 yen left.

Sample Input 2

1000
108
108

Sample Output 2

28

Sample Input 3

579
123
456

Sample Output 3

0

Sample Input 4

7477
549
593

Sample Output 4

405

Solution in PHP (5.6.30) (judge verdict: Wrong Answer)

<?php

fscanf(STDIN,"%d",$a);
fscanf(STDIN,"%d",$b);
fscanf(STDIN,"%d",$c);
fscanf(STDIN,"%d",$amount);

$count=0;


for($y=0; $y<$a; $y++){
$dd = $amount-(500*$y);
    if ($dd==0){
            $count++;
        }
    for($i=0; $i<$a; $i++){
        $dd=$amount-(500*$y) -(100*$i);
        if ($dd==0){
            $count++;
        }
        for($x=0; $x<$b; $x++ ){
           $dd=$amount-(50*$x) -(100*$i)-(500*$y);
           if ($dd==0){
                $count++;
            }
        }
    }
}
    
   


echo $count;
?>