import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        long N;
        long K;
        try (Scanner sc = new Scanner(System.in)) {
            N = sc.nextLong();
            K = sc.nextLong();
        }
        if (N > K) {
            N = N % K;
        }
        if (K - N > N) {
            System.out.println(N);
        } else {
            System.out.println(K - N);
        }
    }
}

/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