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[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	}

} 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[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	}

} 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[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	} main {
		Scanner sc = new Scanner(System.in);
		int n = Integer.parseInt(sc.next());
		int l = Integer.parseInt(sc.next());
		int[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	} 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[] a = new int[n]; a new int[n] n int absMin = 1000; absMin 1000 for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		} {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		} if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			} Math.abs(l + i) < Math.abs(absMin) Math.abs(l + i) Math.abs Math l + i l i Math.abs(absMin) Math.abs Math absMin {
				absMin = l + i;
			} absMin = l + i absMin l + i l i a[i] = l + i a[i] a i l + i l i int sum = 0; sum 0 for (int i = 0; i < n; i++) {
			sum += a[i];
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			sum += a[i];
		} {
			sum += a[i];
		} sum += a[i] sum a[i] a i sum -= absMin sum absMin System.out.println(sum) System.out.println System.out System System.out sum 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[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	}

} 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[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	}

} 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[] a = new int[n];
		int absMin = 1000;
		for (int i = 0; i < n; i++) {
			if (Math.abs(l + i) < Math.abs(absMin)) {
				absMin = l + i;
			}
			a[i] = l + i;
		}
		int sum = 0;
		for (int i = 0; i < n; i++) {
			sum += a[i];
		}
		sum -= absMin;
		System.out.println(sum);

	}

}
