import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    }
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.util.Arrays; Arrays java.util import java.util.StringTokenizer; StringTokenizer java.util public class Main {
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    }
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
} Main public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    } main {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    } FastReader sc = new FastReader(); sc new FastReader() int N = sc.nextInt(); N sc.nextInt() sc.nextInt sc int L = sc.nextInt(); L sc.nextInt() sc.nextInt sc int[] arr = new int[N+1]; arr new int[N+1] N+1 N 1 for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
            arr[i] = i+L-1;
        } {
            arr[i] = i+L-1;
        } arr[i] = i+L-1 arr[i] arr i i+L-1 i+L i L 1 int mindist = 0x3f3f3f3f; mindist 0x3f3f3f3f int minpos = 0; minpos 0 for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        } {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        } if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            } Math.abs(arr[i])<mindist Math.abs(arr[i]) Math.abs Math arr[i] arr i mindist {
                mindist = Math.abs(arr[i]);
                minpos = i;
            } mindist = Math.abs(arr[i]) mindist Math.abs(arr[i]) Math.abs Math arr[i] arr i minpos = i minpos i arr[minpos] = 0 arr[minpos] arr minpos 0 int sum = 0; sum 0 for (int i=1; i<=N; i++) {
            sum += arr[i];
        } int i=1; int i=1; i 1 i<=N i N i++ i++ i {
            sum += arr[i];
        } {
            sum += arr[i];
        } sum += arr[i] sum arr[i] arr i System.out.println(sum) System.out.println System.out System System.out sum String[] args args static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    } FastReader BufferedReader br; br StringTokenizer st; st public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        } FastReader {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        } br = new BufferedReader(new
                    InputStreamReader(System.in)) br new BufferedReader(new
                    InputStreamReader(System.in)) String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        } next {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        } while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            } st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            } try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                } catch (IOException e)
                {
                    e.printStackTrace();
                } IOException e {
                    e.printStackTrace();
                } e.printStackTrace() e.printStackTrace e {
                    st = new StringTokenizer(br.readLine());
                } st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt()
        {
            return Integer.parseInt(next());
        } nextInt {
            return Integer.parseInt(next());
        } return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong()
        {
            return Long.parseLong(next());
        } nextLong {
            return Long.parseLong(next());
        } return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble()
        {
            return Double.parseDouble(next());
        } nextDouble {
            return Double.parseDouble(next());
        } return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        } nextLine {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        } String str = ""; str "" try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            } catch (IOException e)
            {
                e.printStackTrace();
            } IOException e {
                e.printStackTrace();
            } e.printStackTrace() e.printStackTrace e {
                str = br.readLine();
            } str = br.readLine() str br.readLine() br.readLine br return str; str public class Main {
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    }
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
} public class Main {
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    }
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {
    public static void main(String[] args) {
        FastReader sc = new FastReader();
        int N = sc.nextInt();
        int L = sc.nextInt();
        int[] arr = new int[N+1];
        for (int i=1; i<=N; i++) {
            arr[i] = i+L-1;
        }
        int mindist = 0x3f3f3f3f;
        int minpos = 0;
        for (int i=1; i<=N; i++) {
            if (Math.abs(arr[i])<mindist) {
                mindist = Math.abs(arr[i]);
                minpos = i;
            }
        }
        arr[minpos] = 0;
        int sum = 0;
        for (int i=1; i<=N; i++) {
            sum += arr[i];
        }
        System.out.println(sum);
    }
    static class FastReader
    {
        BufferedReader br;
        StringTokenizer st;

        public FastReader()
        {
            br = new BufferedReader(new
                    InputStreamReader(System.in));
        }

        String next()
        {
            while (st == null || !st.hasMoreElements())
            {
                try
                {
                    st = new StringTokenizer(br.readLine());
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt()
        {
            return Integer.parseInt(next());
        }

        long nextLong()
        {
            return Long.parseLong(next());
        }

        double nextDouble()
        {
            return Double.parseDouble(next());
        }

        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
}
