import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt(), L = sc.nextInt();
		Map<Integer, Integer> map = new TreeMap<>();
		int sum = 0;
		for(int i = 1; i <= N; i++) {
			sum += L+i-1;
			map.put(Math.abs(L+i-1),i);
		}
		int le = 0;
		for(Map.Entry<Integer, Integer> entry : map.entrySet()) {
			le = entry.getValue();
			break;
		}
		sum -= L+le-1;
		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