
import java.util.Scanner;

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