import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner scan=new Scanner(System.in);
		long N=scan.nextLong();
		long K=scan.nextLong();
		long min=N;
		N=N%K;
		min=N;
		while(min>Math.abs(N-K)){
			N=Math.abs(N-K);
			min=Math.min(min,N);
		}
		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