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[] apple = new int[n];

        for(int i = 0; i < n; i++){
            apple[i] = l + i;
        }
        int sum = 0;

        for (int i = 0; i < n; i++)
            sum += apple[i];
        System.out.println(sum - abs_min(apple));
        sc.close();  
    }

    static int abs_min(int[] a){
        int min = a[0];
        for (int i = 1; i < a.length; i++){
            if (Math.abs(a[i]) < Math.abs(min))
                min = a[i];
        }
        return min;
    }
}
/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