import java.util.Scanner;

public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    }
} import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    }
} Main public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    } main {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int n = sc.nextInt(); n sc.nextInt() sc.nextInt sc int l = sc.nextInt(); l sc.nextInt() sc.nextInt sc int[] taste = new int[n]; taste new int[n] n int eat=200; eat 200 int pai=0; pai 0 for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        } int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        } {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        } taste[i] = l+i taste[i] taste i l+i l i pai+=l+i pai l+i l i if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            } Math.abs(taste[i]) < Math.abs(eat) Math.abs(taste[i]) Math.abs Math taste[i] taste i Math.abs(eat) Math.abs Math eat {
                eat = taste[i];
            } eat = taste[i] eat taste[i] taste i System.out.println(pai - eat) System.out.println System.out System System.out pai - eat pai eat String[] args args public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    }
} public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    }
} Main
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int l = sc.nextInt();
        int[] taste = new int[n];
        int eat=200;
        int pai=0;

        for (int i = 0; i < n; i++) {
            taste[i] = l+i;
            pai+=l+i;
            if (Math.abs(taste[i]) < Math.abs(eat)) {
                eat = taste[i];
            }
        }

        System.out.println(pai - eat);
    }
}