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 res = n % k;
    
    System.out.println(Math.min(Math.abs(res-k),res));
  } 
}
/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