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 Fortran (gfortran v4.8.4) (judge verdict: Runtime Error)

program probC
  implicit none
  integer*8,allocatable :: ame(:,:)
  integer*8 N,j,tot,i

  read(*,*) N
  allocate(ame(0:n+1,2))
  ame=0

  read(*,*) ame(1:n,1)
  read(*,*) ame(1:n,2)


  tot=0
  do j=1,n
     tot=tot+ame(j,1)
     if(sum(ame(j+1:n,1))>=sum(ame(j:n-1,2))) then
     else
        tot=tot+sum(ame(j:n-1,2))
        exit
     end if
  end do
  tot=tot+ame(n,2)
  
  write(*,*) tot
  
end program probC