import java.io.*;
import java.util.StringTokenizer;

import static java.lang.Math.*;

public class Main {
  public static void main(String[] args) {
    new Main().solve();
  }

  private void solve() {
    try(InputReader in = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out)) {

      final int n = in.nextInt();
      final int l = in.nextInt();

      int total = 0;
      for (int i = 0; i < n; i++) {
        total += l + i;
      }

      int res = 0;
      for (int i = 0; i < n; i++) {
        int t = 0;
        for (int j = 0; j < n; j++) {
          if(j != i) {
            t += l + j;
          }
        }
        if(abs(total - res) > abs(total - t)) res = t;
      }

      final int ans = res;
      out.println(ans);
    }
    catch(IOException e) {
      System.err.println(e);
    }
  }

  int atoi(String s) { return Integer.parseInt(s); }
  long atol(String s) { return Long.parseLong(s); }

  static class InputReader implements AutoCloseable {
    public BufferedReader br;
    public StringTokenizer st;

    public InputReader(InputStream stream) {
      br = new BufferedReader(new InputStreamReader(stream), 32768);
      st = null;
    }
    public String next() {
      if (st == null || !st.hasMoreTokens()) {
        try { st = new StringTokenizer(br.readLine());
        } catch (IOException e) {
          throw new UncheckedIOException(e);
        }
      }
      return st.nextToken();
    }
    public int nextInt() { return Integer.parseInt(next()); }
    public long nextLong() { return Long.parseLong(next()); }
    int[] mapInt(int len) {
      int[] ret = new int[len];
      for (int i = 0; i < len; i++) ret[i] = Integer.parseInt(next());
      return ret;
    }
    long[] mapLong(int len) {
      long[] ret = new long[len];
      for (int i = 0; i < len; i++) ret[i] = Long.parseLong(next());
      return ret;
    }
    @Override public void close() throws IOException { br.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