import java.util.Scanner;

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 = Long.MAX_VALUE;
        if(n > k){
            n = n - (k * (n / k));
            ans = Long.min(n, Math.abs(n - k));
        } else if(n == k){
            ans = 0;
        } else {
            // (n < k)
            ans = Long.min(n, Math.abs(n - k));
        }
        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