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
  fscanf(STDIN,"%d %d", $n, $k);
  if($n != $k){
    if ($n%2 == 0 && $k%2 == 0){
      if($n < $k) {
        echo "0\n";
      } else {
        echo "2\n";
      }
    } else if ($n%2 == 1 && $k%2 == 1){
      if($n < $k){
        if ($k - $n == 2){
          echo "2\n";
        } else {
          echo $n."\n";
        }
      } else {
        echo $n%$k."\n";
      }
    } else if ($n%2 == 1 && $k%2 == 0 || $n%2 == 0 && $k%2 == 1){
      if ($n < $k){
        echo $n,"\n";
      } else {
        echo $n%$k."\n";
      }
    }
  } else {
    echo "0\n";
  }
?>