import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt(),l=sc.nextInt();
        int minabs=Integer.MAX_VALUE;
        int ans=0,finalans=0;
        for(int i=0;i<n;i++){
            ans+=l+i;
        }
        for(int i=0;i<n;i++){
            if(minabs>Math.abs(l+i)){
                finalans=ans-(l+i);
                minabs=Math.abs(l+i);
            }
        }
        System.out.println(finalans);
    }

}
/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