import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc=new Scanner(System.in);
		
		int n=sc.nextInt();	
		int a=sc.nextInt();	
		
		 int l=a;
		 int r=a+n-1;
		 int eat=0;
		 
		 if(r<=0) {
			 eat=r;
		 }else if(l>=0) {
			 eat=l;
		 }else {
			eat=0;
		 }
		int answer=(r+l)*(r-l+1)/2-eat;
		System.out.println(answer);
		sc.close();
	}

}
/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