import java.util.*;

import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Main {
	
	
	
	
    public static void main(String[] args) {
    	Scanner sc=new Scanner(System.in);
    	long  n=sc.nextLong();
    	long k=sc.nextLong();
    	long min=Integer.MIN_VALUE;
    	System.out.println(Math.min(n%k, k-(n%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