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: Wrong Answer)

<?php

$k = trim(fgets(STDIN));

$que = [];
$count = 0;
for($i = 1; $i <= 9; $i++) {
    $que[] = $i;
    $count++;
    if ($count == $k) {
        print $i;
        return;
    }
}

while (true) {
    $num = array_shift($que);
    if ($num % 10 != 0) bfs(10*$num-1);
    bfs(10*$num);
    if ($num % 10 != 9) bfs(10*$num+1);
}

function bfs($num) {
    global $que, $count, $k;
    $que[] = $num;
//    print $num . "\n";
    $count++;
    if ($count == $k) {
        print $num;
        exit;
    }
}