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 Python (3.4.3) (judge verdict: Runtime Error)

big = int(input())
mid = int(input())
small = int(input())
input_money = int(input())

cnt = 0
for i in range(big+1):
    for j in range(mid+1):
        for k in range(small+1):
            if (input_money-500*i)>=0:
                money = (input_money-500*i)
                if money==0:
                    cnt += 1
                    break
                if (money-100*j)>=0:
                    money = (money-100*i)
                    if money==0:
                        cnt += 1
                        break
                    if (money-50*j)>=0:
                        money = (money-50*i)
                        if money==0:
                            cnt += 1
                            break
            else:
                continue
            break

print(cnt)