import java.util.*;

import javax.swing.plaf.basic.BasicSliderUI.ScrollListener;

public class Main {
    static public void main(String args[]) {

        Scanner sc = new Scanner(System.in);
        String temp = sc.next();
        long n = Long.parseLong(temp);
        temp = sc.next();
        long k = Long.parseLong(temp);

        long temp2 = n % k;
        if (temp2 > k / 2) {
            temp2 = k - temp2;
        }
        System.out.println(temp2);
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz