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();
        n = n % k;
        while (true) {
            long tmp = Math.abs(k - n);
            if (tmp >= n) {
                break;
            }
            n = tmp;
        }
        System.out.println(n);
    }
}

/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