import java.util.*;
public class Main {
    public static void main(String [] args){
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int L = sc.nextInt();
        int sum=0,opt = 999999999,opt_num=0;
        for(int i=1;i<=N;i++) {
            int num = L+i-1;
            sum+=num;
            if(opt>Math.abs(L+i-1)){
                opt = Math.abs(L+i-1);
                opt_num = L+i-1;
            }
        }
        System.out.println(sum-opt_num);
    }
}

/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