import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner stdIn = new Scanner(System.in);
        long N = stdIn.nextLong();
        long K = stdIn.nextLong();

        long min = ((N % K) > Math.abs((N % K) - K)) ?  Math.abs((N % K) - K) : (N % K);

        System.out.println(min);
    }
}
/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