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 sum = 0;
    int min = 300;
    int apple = min;
    for(int i=1;i<=N;i++){
      int d = L+i-1;
      sum+=d;
      if(Math.abs(d)<min){
        min = Math.abs(d);
        apple = d;
      }
    }
    System.out.println(sum-apple);
  }
}
/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