import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      int n = Integer.parseInt(sc.next());
      int l = Integer.parseInt(sc.next());
      int[] taste = new int[n];
      int sum = 0;
      for(int i=0;i<n;i++){
        taste[i] = l+i;
        sum+=taste[i];
      }
      int idx = -1;
      int min = 10000000;
      for(int i=0;i<n;i++){
        if(min > Math.abs(taste[i])){
          idx = i;
          min = Math.abs(taste[i]);
        }
      }
      System.out.print(sum-taste[idx]);
      System.out.flush();
    }
}
/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