import java.util.*;
import java.io.*;

public class Main{
  public static void main(String[] args)throws Exception{
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    try{
      String[] S = br.readLine().split(" ");
      long N = Long.parseLong(S[0]);
      long M = Long.parseLong(S[1]);
      
      long mod = N%M;
      System.out.println(Math.min(mod, Math.abs(M-mod))); 
    }catch(Exception e){
    }
  }
}

/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