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[] arr = new int[n];
      int sum = 0;
      for(int i = 0; i < n; i++) {
        arr[i] = l + i;
        sum += arr[i];
      }
      int min = Integer.MAX_VALUE;
      int res = 0;
      for(int i = 0; i < n; i++) {
        if(Math.abs(arr[i]) < min) {
          min = Math.abs(arr[i]);
          res = sum - arr[i];
        }
      }
      System.out.println(res);
  }
}
/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