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 res1 = n % k;
		long res2 = k - n % k;
		if(res1 > res2){
			res1 = res2;
		}
		System.out.println(res1);
	}
}
/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