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 min = Math.abs(l);
        int k = 1;
        int sum = l;
        for (int i = 2; i <= n; i++) {
            if (min > Math.abs(l - 1 + i)) {
                min = Math.abs(l - 1 + i);
                k = i;
            }
            sum += l + i - 1;
        }
        System.out.println(sum - (l + k - 1));
        sc.close();
    }
}
/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