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.math.BigInteger;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String N = sc.next();
        String K = sc.next();
        BigInteger Nsu = new BigInteger(N);
        BigInteger Ksu = new BigInteger(K);
        BigInteger ZERO = BigInteger.ZERO;
        BigInteger TEN = BigInteger.TEN;


        if (Nsu.compareTo(Ksu) == -1) {
            System.out.println(N);
            return;
        } else if (Nsu.bitLength() > 10) {
            Nsu = Nsu.divide(TEN);
        }

        while (Nsu.compareTo(ZERO) == 1) {
            Nsu = Nsu.subtract(Ksu);
        }

        System.out.println(Nsu.abs());
    }
}