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 Rust (1.15.1) (judge verdict: Accepted)

mod io{
    use std::io::*;
    pub fn read<T: ::std::str::FromStr>()->T{
        let stdin=stdin();
        let ret=stdin.lock().bytes().map(|c|c.unwrap()as char)
        .skip_while(|c|c.is_whitespace())
        .take_while(|c|!c.is_whitespace())
        .collect::<String>().parse().ok().unwrap();
        ret
    }
}
use io::read;
fn main(){
    let a=read::<i32>();
    let b=read::<i32>();
    let c=read::<i32>();
    println!("{}",(a-b)%c)
}