import java.util.Scanner;
import java.lang.Math;

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());
        System.out.println(value(N,K));
    }

    public static long value(long N, long K) {
        if (N%K > K-(N%K)) {
            return K - (N%K);
        }

        else {
            return N%K;
        }
    }
}



/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