import java.util.Scanner;
class Main{
public static void main(String[] args){
 Scanner scan = new Scanner(System.in);
 
 long N = scan.nextLong();
 long K = scan.nextLong();
 long x = N % K;
 long y = Math.abs(K - x);
    if(x > y){
      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