import java.*;
import java.util.*;
 
public class Main {
    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
		long number = Long.parseLong(sc.next());
      	long constNum = Long.parseLong(sc.next());
      	long answer=number%constNum;
      	while(true){
        	long afterNum=Math.abs(answer-constNum);
          	if(answer<=afterNum){
              	break;
            }
          	answer=afterNum;
        }
      System.out.println(answer);
    }
}
/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