import java.util.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        long N = sc.nextLong();
        long K = sc.nextLong();
        long now = 0;
        long min = N;

        now = N % K;
        do{
            now = Math.abs(now - K);
            if(min > now) {
               min = now;
            }
        }while(N % K != now);
        System.out.println(min);
    }
}
/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