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.Scanner;

public class Main {
	public static void main (String args[]) {
		Scanner scan = new Scanner(System.in);
		long n = scan.nextLong();
		long k = scan.nextLong();
		long ans = 0;
		boolean loop = true;
		
		if(n == 0) {
			loop = false;
		}
      
      	if(k == 1) {
			loop = false;
		}
      	long x = n;
		if(x > k) {
			long a = x / k;
			x = x - (k * a);
			if(x == 0) {
				loop = false;
			}
		} else if(x == k){
			loop = false;
		}
      	
		long pre = x;
		while(loop) {			
			x = x - k;
			if( x == 0) {
				loop = false;
			}
			if(x < 0) {
				loop = false;
                x = Math.abs(x);
				if(x < pre) {
					ans = x;
				} else {
					ans = pre;
				}
			}
			
			pre = Math.abs(x);
		}
				
		System.out.println(ans);
	}
}