import java.util.Scanner;

public class Main {
	public static void main(String[] args){
		try(Scanner sc = new Scanner(System.in)) {
			
			long n = sc.nextLong();
			long k = sc.nextLong();
			
			long residual = n % k;
			
			long minus = k - residual;
			
			if ( residual < minus ) {
				System.out.println(residual);
			}
			else {
				System.out.println(minus);
			}
		}
	}

}
/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