import java.util.*;

class Main {
  public static void main(String[] args) {
	Scanner sc = new Scanner(System.in);
    
    long x = sc.nextLong(); //next(文字列), nextDouble, nextLine(1行)とか
    long y = sc.nextLong();
    long z = x / y;
    x = x - y*z;
    if (Math.abs(x-y) < x){
      x = Math.abs(x-y);
    }
    
    System.out.println(x);
    
  }
}

/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