import java.util.*;
public class Main {
	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		final long N = in.nextLong();
		final long K = in.nextLong();
		if(N < K) System.out.println(Math.min(N, K - N));
		else {
			long mod = N % K;
			System.out.println((mod == 0) ? 0 : (Math.min(mod, Math.abs(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