import java.util.*;
/**
 * Main
 */
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int L = sc.nextInt();
        int val = (L-1)*N + (N*(N+1))/2 - eatval(N, L);
        System.out.println(val);
        sc.close();
    }

    static int eatval(int N, int L) {
        if(N < -L+1) 
            return L+N-1;
        else if(1 <= -L+1 && -L+1 <= N)
            return 0;
        else
            return L;
    }
}
/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