import java.util.*;
public class Main {
	public static void main(String[] args){
	  Scanner sc = new Scanner(System.in);

      int n = sc.nextInt();
      int l = sc.nextInt();
      
      int[] a = new int[n];
      
      int sum = 0;
      int min = 400;
      int b = 0;
      for(int i = 0; i < n; i++) {
        a[i] = l;
        sum+= l;
        if(min > Math.abs(a[i])) {
          min = Math.abs(a[i]);
          b = a[i];
        }
        l++;
      }
      
           System.out.println(sum - b);
           
           
      
           

      
	}
}
/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