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  
$stdin1 = trim(fgets(STDIN));  
$array1 = explode(' ', $stdin1);
$numA = $array1[0];
$numB = $array1[1];
$lastNum = $numA;
$flg = 0;

while (true) {
  if ($numA % $numB === 0) {
    echo 0;
    break;
  }
  
  if ($numB * 1000 < $numA) {
    $numB = $numB * 1000;
    $flg = 1;
    break;
  }

  $numA = abs($numA - $numB);
  
  if ($lastNum <= $numA) {
    if ($flg === 1) {
      $numB = $numB / 1000;
    } else{
      echo $lastNum;
      break;
    }
  }
  $lastNum = $numA;
}