import java.io.*;
import java.util.*;

class Main {
    public static void main(String args[]) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String[] ips = br.readLine().split(" ");
        long n = Long.parseLong(ips[0]);
        long k = Long.parseLong(ips[1]);
        if(n >= k)
            n %= k;
        long res = Math.min(n, k-n);
        System.out.println(res);
    }
}
/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