import java.util.Scanner;
class Main {
  public static void main(String args[]){
    Scanner  sc = new Scanner(System.in);
    long n , k ,i,t;
    n = sc.nextLong();
    k = sc.nextLong();
    i = n%k;
    t = Math.abs(k-i);
    if(i > t){
      i = t;
    }
    System.out.println(i);
  }
}

/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