Problem:
Score : 300 points

Problem Statement

Given any integer x, Aoki can do the operation below.

Operation: Replace x with the absolute difference of x and K.

You are given the initial value of an integer N. Find the minimum possible value taken by N after Aoki does the operation zero or more times.

Constraints

0 ≤ N ≤ 10^{18}

1 ≤ K ≤ 10^{18}

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N K

Output

Print the minimum possible value taken by N after Aoki does the operation zero or more times.

Sample Input 1

7 4

Sample Output 1

1

Initially, N=7.

After one operation, N becomes |7-4| = 3.

After two operations, N becomes |3-4| = 1, which is the minimum value taken by N.

Sample Input 2

2 6

Sample Output 2

2

N=2 after zero operations is the minimum.

Sample Input 3

1000000000000000000 1

Sample Output 3

0

Solution in Rust (1.15.1) (judge verdict: Accepted)

fn main() {
    let s = read_line();
    let s = read_num_vec(s, 2);
    let n = s.get(0).unwrap().to_owned();
    let k = s.get(1).unwrap().to_owned();

    println!("{}", std::cmp::min(n % k, (n % k - k).abs()));
}

fn read_line() -> String {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    s.trim_right().to_owned()
}

fn read_num_vec(s: String, length: usize) -> Vec<i64> {
    let mut ws = s.split_whitespace();
    let mut result = vec![];
    for _ in 0..length {
        result.push(ws.next().unwrap().parse().unwrap());
    }
    result
}