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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main(void) {
  int x, a, b;

  printf("Money  : ");  scanf("%d", &x);

  do {
    printf("A value: ");  scanf("%d", &a);
    if (1 <= a && a <= 1000)  break;
  } while (1);
  do {
    printf("B value: ");  scanf("%d", &b);
    if (1 <= b && b <= 1000)  break;
  } while (1);


  x -= a;

  while (x >= b) {
    x -= b;
  }

  printf("Remaing money: %d\n", x);

  return 0;
}