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) {
        Main main = new Main();
        main.run();
    }
    
    // 変数一覧
    long n;
    long k;
    long res;

    public void run() {
        // 入力情報取得
        Scanner sc = new Scanner(System.in);
        n = sc.nextLong();
        k = sc.nextLong();
        sc.close();

        // 解答処理
        solve();
    }
    
    private void solve() {
        a(n%k);
        System.out.println(res);
    }
    
    private void a(long a) {
        if (Math.abs(a - k) <= a) {
            a = Math.abs(a - k);
            a(a);
        } else {
            res = a;
            return;
        }
    }
}