import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner S = new Scanner(System.in);
        long N = S.nextLong();
        long K = S.nextLong();
        long Nx = N % K;
        System.out.println(replace(Nx, K));
        S.close();
    }

    public static long replace(long x, long K) {
        long div = x - K;
        if (div < 0) {
            div = -div;
        }
        if (x <= div) {
            return x;
        }
        return replace(div, 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