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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
 
function input($func = null)
{
    if ($func === null) {
        return trim(fgets(STDIN));
    } else {
        return $func(trim(fgets(STDIN)));
    }
}

function input_array($func = null)
{
    if ($func === null) {
        return explode(' ', input());
    } else {
        return array_map(function ($v) use ($func) {
            return $func($v);
        }, explode(' ', input()));
    }
}

list($N, $K) = input_array('intval');

$r = $N % $K;

$candidate_1 = $r;
$candidate_2 = $K - $r;

if ($candidate_1 <= $candidate_2) {
    echo $candidate_1 . "\n";
} else {
    echo $candidate_2 . "\n";
}