import java.math.BigInteger;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        BigInteger N = scanner.nextBigInteger();
        BigInteger K = scanner.nextBigInteger();
        scanner.close();

        BigInteger a = N.remainder(K);

        if (a.compareTo(K.subtract(a)) > 0) {
            System.out.println(K.subtract(a));
        } else {
            System.out.println(a);
        }
    }
}

/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