import java.util.Scanner;

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

        long ans = scanner.nextLong();
        long K = scanner.nextLong();

        ans %= K;

        while (true) {
            long tmp = ans - K > 0 ? ans - K : K - ans;
            if (ans > tmp) {
                ans = tmp;
            } else {
                break;
            }
        }

        System.out.print(ans);

        scanner.close();
    }
}
/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