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

// 読み取り
fscanf(STDIN, "%d %d", $N, $K );

// 商を計算
$r = (int)($N / $K);

//余り算出
$q = $N % $K;

$min_num = 0;

if ($q!=0) {
  $min_num = abs($q - $K);
  if ($q <= $min_num ) {
    $min_num = $q;
  }
}

echo $min_num;

?>