import java.io.*;
import java.lang.*;

class Main {
  public static void main(String[] args) throws IOException {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    String[] strs = br.readLine().split(" ");
    int N = Integer.parseInt(strs[0]);
    int L = Integer.parseInt(strs[1]);
    int sum = 0, asymptote = 0;
    
    for (int i=1; i <= N; i++) {
      if (i == 1) {
        asymptote = (L+i-1) > -1 ? 999 : -999;
      }
      
      if ((L+i-1) > -1 && asymptote > -1) {
        asymptote = Math.min(asymptote, (L+i-1));
      } else {
        asymptote = Math.max(asymptote, (L+i-1));
      }
      sum += (L+i-1);
    }
    System.out.println(sum - asymptote);
  }
}
/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