import java.util.Scanner;

public class Main {
    public static void main(String[] args) throws Exception {

//    	File file = new File("test.txt");
//    	Scanner sc = new Scanner(file);
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        long k = sc.nextLong();
        sc.close();
        boolean flg = true;
        if(k == 1){
        	System.out.println(0);
        	return;
        }
        n = n % k;
        while(flg){
        	n = Math.abs(n - k);
        	if(n < Math.abs(n - k)) flg = false;
        }
        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