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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.*;
public class Main{
  public static void main (String args[]){
    Scanner sc = new Scanner(System.in);
    
    long n = sc.nextLong();
    long k = sc.nextLong();
    
    long min = 0;
    
    if (n > k){
      long a = n%k;
      if (a > 0){
        min = Math.abs(a-k);
      }
    } else if (n < k){
      long a = k-n;
      if (n < a){
        min = n;
      } else {
        min = a;
      }
    }
    
    System.out.println(min);
  }
}