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 []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	}
} 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 []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	}
} Main public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int l = sc.nextInt();
		int []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	} main {
		
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int l = sc.nextInt();
		int []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	} 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 []a = new int [n]; a new int [n] n for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
			a[i] = l + i;
		} {
			a[i] = l + i;
		} a[i] = l + i a[i] a i l + i l i int min = 100; min 100 int sum = 0; sum 0 for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		} int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		} {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		} if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    } Math.abs(min) > Math.abs(a[j]) Math.abs(min) Math.abs Math min Math.abs(a[j]) Math.abs Math a[j] a j {
				min = a[j];
			    } min = a[j] min a[j] a j sum += a[j] sum a[j] a j System.out.println((sum - min)) System.out.println System.out System System.out (sum - min) sum min 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 []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	}
} public class Main {

	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);
		
		int n = sc.nextInt();
		int l = sc.nextInt();
		int []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	}
} 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 []a = new int [n];
		
		for(int i = 0; i < n ; i++) {
			a[i] = l + i;
		}
		int min = 100;
		int sum = 0;
		
		for(int j = 0; j < n ; j++) {
			if(Math.abs(min) > Math.abs(a[j])) {
				min = a[j];
			    }
			sum += a[j];	
		}
		System.out.println((sum - min));
		
	}
}
