import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        int l = scan.nextInt();
        int min = Math.abs(l);
        int sub = l;
        for(int i = 2; i <= n; i++){
            if(Math.abs(l + i - 1) < min){
                min = Math.abs(l + i - 1);
                sub = l + i - 1;
            }
        }
        int sum = 0;
        for(int i = 1; i <= n; i++){
            sum += l + i - 1;
        }
        System.out.println(sum - sub);
    }
}
/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