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();
		if(n > k) {
			n -= k * (n/k);
			if(k -n < n) {
				System.out.println(k-n);
			}else {
				System.out.println(n);
			}
		}else {
			if(k -n < n) {
				System.out.println(k-n);
			}else {
				System.out.println(n);
			}
		}
	}
}
/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