import java.util.*;
import java.lang.Math;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int ans = (2*l+n-1)*n/2;
      	int e;
      
      	if(l*(l+n-1) <= 0) e = 0;
      	else if(Math.abs(l) < Math.abs(l+n-1)) e = l;
      	else e = l+n-1;
      
      	ans -= e;
      	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