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 Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

var 
	i,j,k,sum: longint;
    loop,loop_2,loop_3,ans: integer;
begin
	readln(loop);
    readln(loop_2);
    readln(loop_3);
    readln(ans);
	for i := 0 to loop do begin
        for j:= 0 to loop_2 do begin
            for k:= 0 to loop_3 do begin
            	//writeln(i * 500);
                //writeln(j * 100);
                //writeln(k * 50);
               	if (i * 500 + j * 100 + k * 50 = ans) then inc(sum); //インクリメント 
            end;
        end; 
     end;
     
     writeln(sum);
     
     //writeln(loop);
     //writeln(loop_2);
     //writeln(loop_3);
 
 
 end.