import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
  	long n,k;
  	n=sc.nextLong();
  	k=sc.nextLong();
  	int f=0;
  	while(f==0){
  		if(n>k){
  			n%=k;
  		}else{
  			if(n<=k-n){
  				break;
  			}else{
  				n=k-n;
  				break;
  			}
  		}
  	}
  	System.out.print(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