import 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 tot = 0, mn = 500000;
		for(int i = 1; i <= n; i++){
			tot = tot + (l + i -1);
			if( Math.abs(mn) > Math.abs(l+i-1) )
				mn = l+i-1;
		}

		tot = tot - mn;
		System.out.println(tot);
	}
}
/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