import java.io.IOException;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) throws IOException {
		Scanner scanner = new Scanner(System.in);

			BigInteger N = scanner.nextBigInteger();
			BigInteger K = scanner.nextBigInteger();

			BigInteger newN = N;

			newN = (N.remainder(K)).abs();


			N = K.subtract(newN);

			if(N.compareTo(newN) == 1) {
				System.out.println(newN);
			}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