import java.util.*;

public class Main {
public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in); 
		
		int N  = keyboard.nextInt();
		int L  = keyboard.nextInt();
		
		int sum = 0;
		int z = 1000;
		
		for(int i = 1; i < N+1; i++){
			sum += L+i-1;
				if(Math.abs(z) > Math.abs(L+i-1)){
					z = L+i-1;
				}
		}

		System.out.println(sum-z);
		keyboard.close();	
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz