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();
        int sum = 0;
        for (int i=0;i<n;i++) {
            sum += l+i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0;i<n;i++) {
            min = Math.min(min, Math.abs(i+l));
        }
      	if (sum > 0) {
        	System.out.println(sum - min);
        } else {
        	System.out.println(sum + min);
        }
        
    }
}
/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