import java.util.*;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
		int b = sc.nextInt();
		int ans = b;
		int sum = b;
		for(int i = 1; i < a; i++){
		    int cost = b + i;
		    sum += cost;
		    if(post(ans) > post(cost)){
		        ans = cost;
		    }
		}
		System.out.println(sum - ans);
	}
	
	public static int post(int a){
	    if(a < 0){
	        return -a;
	    }else{
	        return a;
	    }
	}
}
/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