import java.util.*;
import java.math.BigInteger;

public class Main {

	public static void main(String [] args) {
		Scanner in =new Scanner(System.in);
		String N=in.next();
		String K=in.next();
		BigInteger b =new BigInteger(N);
		BigInteger jian =new BigInteger(K);
		b=b.mod(jian);
		  b=b.min(b.subtract(jian).abs());
		System.out.print(b.toString());

		
	}
}
/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