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 Java8 (OpenJDK 1.8.0) (judge verdict: Runtime Error)

package Abc087;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * @author miyaa
 *
 */
public class Main {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		try {
			int money = Integer.parseInt(in.readLine());
			int cakePrice = Integer.parseInt(in.readLine());
			int donutPrice = Integer.parseInt(in.readLine());

			int result = getBuyingSweetsResult(money, cakePrice, donutPrice);

			System.out.println(result);

		} catch (NumberFormatException e) {
			// TODO 自動生成された catch ブロック
			e.printStackTrace();
		} catch (IOException e) {
			// TODO 自動生成された catch ブロック
			e.printStackTrace();
		}
	}

	/**
	 * @return
	 */
	public static void TestBuyingSweets() {
		System.out.println(getBuyingSweetsResult(1234, 150, 100)); // 84
		System.out.println(getBuyingSweetsResult(1000, 108, 108)); // 28
		System.out.println(getBuyingSweetsResult(579, 123, 456)); // 0
	}

	/**
	 * @param money
	 * @param cakePrice
	 * @param donutPrice
	 * @return
	 */
	public static int getBuyingSweetsResult(int money, int cakePrice, int donutPrice) {
		money -= cakePrice;
		while (money - donutPrice >= 0)
			money -= donutPrice;
		return money;
	}
}