import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long n = Long.parseLong(sc.next());
        long k = Long.parseLong(sc.next());
        if (n % k == 0) {
            System.out.println(0);
            return;
        }
        long mod = Math.abs(n % k - k);
        System.out.println(Math.min(n % k, mod));
    }
}
/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