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();
		sc.close();
		int taste[]=new int[N];
		int alltaste=0;
		int minabs,minnum=0;
		for(int i=0;i<N;i++) {
			taste[i]=Math.abs(L+i);
			alltaste+=L+i;
		}
		minabs=taste[0];
		for(int j=0;j<N;j++) {
			if(minabs>taste[j]) {
				minabs=taste[j];
				minnum=j;
			}
		}
		alltaste=alltaste-(L+minnum);
		System.out.println(alltaste);
	}
}
/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