import java.util.*;
import java.lang.Math;
class Main{
    static Scanner sc=new Scanner(System.in);
    public static void main(String[] args){
        long N = sc.nextLong();
        long K = sc.nextLong();
        long t = N/K;
        long temp1=Math.abs(N-K*t);
        long temp2=Math.abs(temp1-K);
        System.out.println((temp1<=temp2) ? temp1 : temp2);
    }
}
/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