import java.util.Scanner;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    int n = sc.nextInt();
    int l = sc.nextInt();
    int[] taste = new int[n];
    int sum = 0;
    int abs_min = 512;
    int abs_min_index = 512;

    for(int i=0; i<n; ++i) {
      taste[i] = l + (i+1) - 1;
      sum += taste[i];
      if( Math.abs(taste[i]) < abs_min ) {
        abs_min = Math.abs(taste[i]);
        abs_min_index = i;
      }
    }

    sum -= taste[abs_min_index];
    System.out.println(sum);
  }
}
/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