import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        while (sc.hasNext()) {
            int N = sc.nextInt();
            int L = sc.nextInt();

            int[] flavors = new int[N];
            int sum = 0;

            for (int i = 0; i < N; i++) {
                flavors[i] = L + i;
            }

            if ((flavors[0] < 0 && flavors[N-1] == 0) || (flavors[0] < 0 && flavors[N-1] < 0) ){
                for (int i = 0; i < N - 1; i++)
                    sum += flavors[i];
            }else if ((flavors[0] == 0 && flavors[N-1] > 0) || (flavors[0] > 0 && flavors[N-1] > 0) ){
                for (int i = 1; i < N; i++) {
                    sum += flavors[i];
                }
            }else if (flavors[0] < 0 && flavors[N-1] > 0){
                for (int i = 0; i < N; i++) {
                    if (flavors[i] == 0)
                        continue;
                    sum+= flavors[i];
                }
            }

            System.out.println(sum);


        }


    }
}
/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