
import java.util.*;
import java.lang.*;

import static java.lang.StrictMath.abs;

class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int d = sc.nextInt();
        int L = sc.nextInt();
        int[] ans = new int[d];
        int sum =0;
        for(int i =1; i <= d; i++){
            ans[i-1] = L + i -1;
        }
        //もとのアップルパイの味
        for(int j =0; j < d; j++){
            sum += ans[j];
        }
        //食べたあとのアップルパイの味
        
        if(ans[0] > 0){
            System.out.println(sum - ans[0]);
        }
        //０に近いものを食べる
        else if(ans[d-1] < 0){
            System.out.println(sum - ans[d-1]);
        }
        //０に近いものを食べる
        else{
            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