import java.util.*;
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 == 0){
            System.out.println(0);
        }
        else{
            n = n % k;
            if(n > Math.abs(n-k)){
                System.out.println(Math.abs(n-k));
            }
            else{
                System.out.println(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