import java.util.*;
import java.io.*;

public class Main
{
	public static void main(String [] Args)
	{
		Scanner in=new Scanner(System.in);		
		int n=in.nextInt();
		int l=in.nextInt();
		int ans=(l-1)*n+n*(n+1)/2;
		int q=Math.min(Math.abs(l),Math.abs(l+n-1));
		if(l<0&&l+n-1>0)
		{
			ans=ans;
		}
		else if(Math.abs(l)<Math.abs(l+n-1))
		{
			ans=ans-l;
		}
		else
		{
			ans=ans-l-n+1;
		}
		System.out.println(ans);
	}
}
	
/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