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: Wrong Answer)

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		
		String[] command = br.readLine().split(" ");
		long N = Long.parseLong(command[0]);
		long K = Long.parseLong(command[1]);
		
		long a = N / K ;
		long b = N % K;
		
		long result;
		if(b == 0) result = 0;
		
		
		if(a == 0) {
			if(Math.abs(N) > Math.abs(a - b)) {
				result = Math.abs(a - b);
			}else {
				result = Math.abs(N);
			}
		}else{
			long d = a * K;
			long c = N % d;
			if(Math.abs(c) > Math.abs(c - K)) {
				result = Math.abs(c - K);
			}else {
				result = Math.abs(c);
			}
		}
		
		System.out.println(result);
	}

}