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 (1.42.0) (judge verdict: Accepted)

use proconio::input;

fn main() {
    input! {
        n: i64,
        k: i64,
    }

    let mut result = n;

    let t = if n > k || n == 0 { n / k } else { k / n };

    if (n - (t - 1) * k).abs() < result {
        result = (n - (t - 1) * k).abs();
    }
    if (n - t * k).abs() < result {
        result = (n - t * k).abs();
    }
    if (n - (t + 1) * k).abs() < result {
        result = (n - (t + 1) * k).abs();
    }

    println!("{}", result);


}