import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	} main {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = Integer.parseInt(sc.next()); n Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int l = Integer.parseInt(sc.next()); l Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int minAbs = 100; minAbs 100 int sum = 0; sum 0 for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		} int i = l; int i = l; i l i < l + n i l + n l n i++ i++ i {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		} {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		} sum += i sum i if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			} Math.abs(i) < Math.abs(minAbs) Math.abs(i) Math.abs Math i Math.abs(minAbs) Math.abs Math minAbs {
				minAbs = i;
			} minAbs = i minAbs i System.out.println(sum - minAbs) System.out.println System.out System System.out sum - minAbs sum minAbs String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	}
} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());

		int minAbs = 100;
		int sum = 0;

		for (int i = l; i < l + n; i++) {
			sum += i;
			if (Math.abs(i) < Math.abs(minAbs)) {
				minAbs = i;
			}
		}
		System.out.println(sum - minAbs);
	}
}