import java.util.*;
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){
                n = n%k;
            }
            System.out.println(Math.min(n,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