import java.io.*;
import java.lang.*;
import java.util.*;
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        String[] str=br.readLine().split(" ");
        long N=Long.parseLong(str[0]);
        long K=Long.parseLong(str[1]);
        long ans=0;
        N=N%K;
        if(N==0) ans=0;
        else  ans=Math.min(K-N,N);
        System.out.println(ans);
    }
}
/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