import java.util.Scanner;

class Main {
    public static void main(final String[] args) {
        Scanner scan = new Scanner(System.in);
        int N = scan.nextInt();
        int L = scan.nextInt();

        int eat = Integer.MAX_VALUE;
        int sum = 0;
        for (int i = 1; i<=N; i++) {
            int m = L + i -1;
            sum += m;
            if (Math.abs(m) < Math.abs(eat)) {
                eat = m;
            }
        }
        System.out.println(sum - eat);
    }
}

/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