import java.util.*;

 
class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    long k = sc.nextLong();
    
    n = n % k;
    
    if(n == 0){
      System.out.println(0);
      return;
    }
    
    long ans = Math.min(k-n,n);
    System.out.println(ans);
    
  }
}
/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