import java.util.*;
public class Main{
	public static void main(String[] args){
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    }
} import java.util.*; util.* java public class Main{
	public static void main(String[] args){
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    }
} Main public static void main(String[] args){
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    } main {
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    } int sum = 0; sum 0 int all = 0; all 0 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[] array = new int[n]; array new int[n] n int[] array2 = new int[n]; array2 new int[n] n for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	} int i = 0; int i = 0; i 0 i < n i n i++ i++ i {
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	} {
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	} array[i] = l+i array[i] array i l+i l i array2[i] = Math.abs(array[i]) array2[i] array2 i Math.abs(array[i]) Math.abs Math array[i] array i sum = array2[0] sum array2[0] array2 0 for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        } int j = 0; int j = 0; j 0 j < n j n j++ j++ j {
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        } {
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        } sum = Math.min(sum, array2[j]) sum Math.min(sum, array2[j]) Math.min Math sum array2[j] array2 j if(sum == array2[j]) {all = array[j];} sum == array2[j] sum array2[j] array2 j {all = array[j];} all = array[j] all array[j] array j System.out.println((n*(l*2+n-1))/2-all) System.out.println System.out System System.out (n*(l*2+n-1))/2-all (n*(l*2+n-1))/2 (n*(l*2+n-1)) n (l*2+n-1) l*2+n l*2 l 2 n 1 2 all sc.close() sc.close sc String[] args args public class Main{
	public static void main(String[] args){
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    }
} public class Main{
	public static void main(String[] args){
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    }
} Main
import java.util.*;
public class Main{
	public static void main(String[] args){
		int sum = 0;
		int all = 0;
    	Scanner sc = new Scanner(System.in);
      	int n = sc.nextInt();
      	int l = sc.nextInt();
      	int[] array = new int[n];
      	int[] array2 = new int[n];
      	for(int i = 0;i < n;i++){
      		array[i] = l+i;
          	array2[i] = Math.abs(array[i]);
      	}
      	sum = array2[0];
      	for(int j = 0;j < n;j++){
      		sum = Math.min(sum, array2[j]);
      		if(sum == array2[j]) {all = array[j];}
        }
      	System.out.println((n*(l*2+n-1))/2-all);
      	sc.close();
    }
}