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)

#![allow(dead_code)]
#![allow(unused_variables)]
#![allow(unused_variables)]

use std::io::stdin;
use std::str::FromStr;
use std::cmp::min;

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

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

fn read_n_vec<T: FromStr>(n: u32) -> Vec<Vec<T>> {
    let mut v_outer = Vec::new();
    for _ in 0..n {
        let v_inner = read_vec();
        v_outer.push(v_inner);
    }
    v_outer
}

fn main() {
    let line: Vec<u64> = read_vec();
    let n = line[0];
    let k = line[1];

    let rem = n % k;
    println!("{}", min(rem, k - rem));
}