import java.util.*;
        public class Main {
        	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		long k = sc.nextLong();
		long x=n/k;
		if(Math.abs(n-x*k)<Math.abs(n-(x+1)*k)){

			System.out.print(Math.abs(n-x*k));
		}else{
			System.out.print(Math.abs(n-(x+1)*k));
		}
	}
        }
/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