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 JavaScript (node.js v5.12) (judge verdict: Wrong Answer)

function main(input) {
  const args = input.split('\n');
  const A = parseInt(args[0]); const B = parseInt(args[1]);
  const C = parseInt(args[2]); const X = parseInt(args[3]);
  
  var cnt = 0;
  for (var a = 0; a <= A; ++a) {
    for (var b = 0; b <= B; ++b) {
      for (var c = 0; c <= C; ++c) {
        var x = 500*a + 100*b + 50*c;
        if (x === X) {
          ++cnt;
        }
      }
    }
  }
  console.log(cnt);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'))