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 N_min= 0;
		
			if (N<=K){
			N_min=Math.min(Math.abs(N-K),Math.abs(N));
			System.out.println(N_min);
			}
			else{
			N_min=Math.min(N%K,Math.abs((N%K)-K));
			System.out.println(N_min);
			}
		}
    }
/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