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();
        sc.close();

        if (k == 0) {
            System.out.print(n);
            return;
        }

        if (n < k)
        {
            long ans = Math.min(n, Math.abs(n - k));
            System.out.print(ans);
            return;
        }

        long count = n / k;//n > k
        long biggerK = k * (count + 1);
        long smallerK = k * (count);
        long ans = Math.min(Math.min(n, Math.abs(n - biggerK)), Math.abs(n - smallerK));
        System.out.print(ans);
    }
}
/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