import java.util.Scanner;

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_abs = Integer.MAX_VALUE;
        int min = Integer.MAX_VALUE;

        for (int i = 0; i < n; i++) {
            int tmp = l + i;
            sum += tmp;
            if (min_abs > Math.abs(tmp)) {
                min = tmp;
                min_abs = Math.abs(tmp);
            }
        }

        System.out.println(sum - 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