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: Accepted)

import java.util.Scanner;

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

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int money = sc.nextInt();
		int cakePrice = sc.nextInt();
		int donutPrice = sc.nextInt();

		int result = getBuyingSweetsResult(money, cakePrice, donutPrice);
		System.out.println(result);
	}

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