import java.util.Scanner;
public class Main{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int sum = 0;
        if (a + b >= 0 && b >= 0) {
            for (int i = 0; i < a - 1; i++) {
                sum += b + 1 + i;
            }
        }
        if (a + b > 0 && b < 0) {
            for (int i = 0; i < a; i++) {
                sum += b + (i);
            }
        }
        if (a + b <= 0 && b < 0) {
            for (int i = 0; i < a - 1; i++) {
                sum += b + (i);
            }
        }
        System.out.println(sum);
    }
}
/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