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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include "stdio.h"

int main(void){
  int A,B,C,X;
  int N,M,L;
  int count = 0;

  scanf("%d%d%d%d", &A, &B, &C, &X);

  for(int i=0;i<=A;i++){
    if(X != 0){
      N = X - 500*i;
      if(N == 0){
        count++;
      }
    }
    for(int j=0;j<=B;j++){
      if(N != 0){
        M = N - 100*j;
        if(M == 0){
          count++;
        }
      }
      for(int k=0;k<=C;k++){
        if(M != 0){
          L = M - 50*k;
          if(L == 0){
            count++;
          }
        }
      }
    }
  }
  printf("%d", count);

  return 0;
}