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 PHP (5.6.30) (judge verdict: Wrong Answer)

<?php

$default = explode(" ", trim(fgets(STDIN)));

if($default[0] > $default[1]){
	$t = $default[0] % $default[1];
	if($t > $default[1]-$t){
		$ans = $default[1]-$t;
	}else{
		$ans = $t;
	}
}

if($default[1] > $default[0]){
	$t = $default[1] % $default[0];
	if($t > $default[0]-$t){
		$ans = $default[1]-$t;
	}else{
		$ans = $t;
	}
}

echo $ans;