import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long k = sc.nextLong();
        Set<Long> s = new HashSet<>();

        long min = n;
        while (!s.contains(n)) {
            if (n % k == 0) {
                min = 0;
                break;
            }

            s.add(n);
            if (n > k) n = n % k;
            else n = Math.abs(n-k);
            min = Math.min(min, n);
        }

        System.out.println(min);
    }
}
/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