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: Runtime Error)

    function main(input){
        const lines = input.split(/\n/);
        const coin500 = parseInt(lines[0]);
        const coin100 = parseInt(lines[1]);
        const coin50 = parseInt(lines[2]);
        const goal = parseInt(lines[3]);
        let count = 0;
        end:
        for(var i = 0; i <= coin500; i++){
            for(var j = 0; j <= coin100; j++){
                for(var k = 0; k < coin50; k++){
                    if(i * 500 + j * 100 + k * 50 === goal){
                        count++;
                    }
                }   
            }
        }
        console.log(count);
    }
    main(require('fs').readFileSync('/dev/stdin','utf-8'));