import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int l = scanner.nextInt();

        List<Integer> diff = new ArrayList<Integer>();
        
        for(int i = 1; i < n+1; i++) {
          int value = l+i-1;
          if(value < 0) {
            value = value * -1;
          }
          diff.add(value);
          }
        
        Integer removeK = diff.indexOf(Collections.min(diff)) + 1;
        
        
        System.out.println(n*l + n*(n+1)/2 - n - (l+ removeK -1));
    }
}
/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