import java.util.*;
public class Main {//ここが Main になっている
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        Long N = Long.parseLong(sc.next());
        Long K = Long.parseLong(sc.next());
        Long next_n;
        Long t = N % K;
        Long k_t = K - t;
        if (t<k_t){
            System.out.println(t);
        }
        if (t>=k_t){
            System.out.println(k_t);
        }
    }
}

/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