import java.util.Scanner;

public class Main{ public static void main(String...args){
        Scanner sc = new Scanner(System.in); long N = sc.nextLong(); long K = sc.nextLong(); long res = N % K;
        System.out.println(Math.min(res, K - 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