import java.util.*;
import java.lang.Math;

public class Main {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		
		Scanner cin = new Scanner(System.in);
		long N = cin.nextLong();
		long K = cin.nextLong();
		
		long min = N%K;
		
		if(min>Math.abs(min-K)) min = Math.abs(min-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