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 ans = N;
		if(N > K){
			N = N - (K * (N / K));
		}
		for(int i = 0;i < 2;i++){
			N = Math.abs(N - K);
			if(N < ans){
				ans = N;
			}
		}
		System.out.println(ans);
	}
}
/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