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: Time Limit Exceeded)

<?php
    fscanf(STDIN,"%d %d",$n,$k);
    while(true){
        if(strlen($n) > strlen($k)+1){
            $n = $n - $k * pow(10,strlen($n)-1);
        }else{
            $ans = abs($n-$k);
            if($n > $ans){
                $n = $ans;
                continue;
            }else{
                break;
            }
        }
    }
    echo $n.PHP_EOL;
?>