import java.util.Scanner;

public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		long N = scan.nextLong();
		long K = scan.nextLong();
		long result = 0;

			if(N%K==0) {
			result = 0;
		}else {
			if(N%K<K-N%K) {
				result = N%K;
			}else {
				result = K-N%K;
			}
		}
		System.out.println(result);
	}
}
/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