import java.util.*;

public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
		long n = scan.nextLong();
		long k = scan.nextLong();

		boolean flag = true;
		if ( n > k){
			long w = n / k;
			n = n - (k*w);
		}
		while(flag){
			long min = 0;
			if( n < k){
				min = k - n;
			}else{
				min = n -k;
			}
			if(n <= min){
				flag = false;
			}else{
				n =min;
			}
		}
		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