import java.util.Scanner;
public class Main
{
	public static void main(String[] args)
    {
     	 Scanner sc = new Scanner(System.in);
      	
     	String[] sep = sc.nextLine().split(" ");
      	long n = Long.parseLong(sep[0]);
      	long k = Long.parseLong(sep[1]);
      	
      	Long min = n % k;
      	if(min > (k - min))
        {
         	System.out.println(k - min); 
        }else{
         	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