import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
		int N = Integer.parseInt(sc.next());
        int L = Integer.parseInt(sc.next());
        int tasteOfPie = 0;
        int minApple = 300;
        int minIndex = 0;
        for (int i = 1; i < N+1; ++i){
            int taste =  L + i - 1;
            tasteOfPie += taste;
            if (minApple > Math.abs(taste)){
                minApple = Math.abs(taste);
                minIndex = i;
            }
        }
        System.out.println(tasteOfPie - (L+minIndex-1));
    }
}
/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