import java.util.*;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    long n = scanner.nextLong();
    long k = scanner.nextLong();
    long r = n%k;
    
    long ans = Math.min(r, (k-r));
    System.out.println(ans);
    scanner.close();
  }

	
}

/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