import java.util.Scanner;
public class Main {
  public static void main(String[] args){
    Scanner scan = new Scanner(System.in);
    int n = scan.nextInt();
    int l = scan.nextInt();
    int bited = 300;
    int sum = 0;
    for(int i = l; i < l + n; i++){
      sum += i;
      if(Math.abs(i) < Math.abs(bited)){
        bited = i;
      }
    }
    System.out.println(sum - bited);
  }
}
/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