import java.io.*;
import java.math.BigInteger;
import java.util.*;
import java.util.Map.Entry;


public class  Main{
    public static void main(String[] args) throws Exception{
    	MScanner sc = new MScanner(System.in);
        //MScanner sc = new MScanner("reduce.in");
        PrintWriter pw=new PrintWriter(System.out);
        //int n=sc.nextInt();
        //Integer[]in=new Integer[n];for(int i=0;i<n;i++)in[i]=sc.nextInt();
        int n=sc.nextInt();int l=sc.nextInt();
        int min=1000000000;int sign=1;int sum=0;
        for(int i=0;i<n;i++) {
        	sum+=l+i;
        	if(Math.abs(l+i)<min) {
        		min=Math.abs(l+i);
        		if(l+i<0)sign=-1;
        		else
        			sign=1;
        	}
        }
        sum-=min*sign;
        pw.println(sum);
        pw.flush();
    }
    static StringBuilder tosb(int[]in) {
    	StringBuilder s=new StringBuilder();
    	for(int i=0;i<in.length;i++) {
    		s.append(in[i]+" ");
    	}
    	return s;
    }
    static StringBuilder tosb(long[]in) {
    	StringBuilder s=new StringBuilder();
    	for(int i=0;i<in.length;i++) {
    		s.append(in[i]+" ");
    	}
    	return s;
    }
    
    static class MScanner {
		StringTokenizer st;
		BufferedReader br;
 
		public MScanner(InputStream system) {
			br = new BufferedReader(new InputStreamReader(system));
		}
 
		public MScanner(String file) throws Exception {
			br = new BufferedReader(new FileReader(file));
		}
 
		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}
 
		public String nextLine() throws IOException {
			return br.readLine();
		}
 
		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}
 
		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}
 
		public char nextChar() throws IOException {
			return next().charAt(0);
		}
 
		public Long nextLong() throws IOException {
			return Long.parseLong(next());
		}
 
		public boolean ready() throws IOException {
			return br.ready();
		}
 
		public void waitForInput() throws InterruptedException {
			Thread.sleep(3000);
		}
	}
}
/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