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)

fn main() {
    let x: i32 = read();
    let a: i32 = read();
    let b: i32 = read();

    let ans = (x - a) % b;
    println!("{}", ans)
}


fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

//fn read_vec<T: std::str::FromStr>() -> Vec<T> {
//    let mut s = String::new();
//    std::io::stdin().read_line(&mut s).ok();
//    s.trim().split_whitespace()
//        .map(|e| e.parse().ok().unwrap()).collect()
//}

//fn read_vec2<T: std::str::FromStr>(n: u32) -> Vec<Vec<T>> {
//    let mut v2 = Vec::new();
//    for _ in 0..n {
//        let mut s = String::new();
//        std::io::stdin().read_line(&mut s).ok();
//        let v = s.trim().split_whitespace()
//            .map(|e| e.parse().ok().unwrap()).collect();
//        v2.push(v);
//    }
//    v2
//}