import java.util.*;
import java.math.RoundingMode;
import java.math.BigDecimal;

public class Main{
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		long k = sc.nextLong();
		if(n>k&&k!=1) {
			long mod = n%k;
			long ans = Math.min(mod, Math.abs(k-mod));
			System.out.println(ans);
		}
		else if(n<k&&k!=1) {
			System.out.println(Math.min(n,k-n));
		}
		else {
			System.out.println(0);
		}
		
	}
}
/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