import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC131_b {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        }

    }
}
 import java.io.OutputStream; OutputStream java.io import java.io.IOException; IOException java.io import java.io.InputStream; InputStream java.io import java.io.PrintWriter; PrintWriter java.io import java.util.Scanner; Scanner java.util public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC131_b {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        }

    }
} Main public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out Scanner in = new Scanner(inputStream); in new Scanner(inputStream) PrintWriter out = new PrintWriter(outputStream); out new PrintWriter(outputStream) ABC131_b solver = new ABC131_b(); solver new ABC131_b() solver.solve(1, in, out) solver.solve solver 1 in out out.close() out.close out String[] args args static class ABC131_b {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        }

    } ABC131_b public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        } solve {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        } int N = in.nextInt(); N in.nextInt() in.nextInt in int L = in.nextInt(); L in.nextInt() in.nextInt in int small = 999; small 999 int small_noneabs = 0; small_noneabs 0 int ttl = 0; ttl 0 for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            } int i = 0; int i = 0; i 0 i < N i N i++ i++ i {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            } {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            } if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                } small > Math.abs(L + i) small Math.abs(L + i) Math.abs Math L + i L i {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                } small = Math.abs(L + i) small Math.abs(L + i) Math.abs Math L + i L i small_noneabs = L + i small_noneabs L + i L i ttl += L + i ttl L + i L i out.println(ttl - small_noneabs) out.println out ttl - small_noneabs ttl small_noneabs int testNumber testNumber Scanner in in PrintWriter out out public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC131_b {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        }

    }
} public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC131_b {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        }

    }
} Main
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        ABC131_b solver = new ABC131_b();
        solver.solve(1, in, out);
        out.close();
    }

    static class ABC131_b {
        public void solve(int testNumber, Scanner in, PrintWriter out) {
            int N = in.nextInt();
            int L = in.nextInt();

            int small = 999;
            int small_noneabs = 0;
            int ttl = 0;
            for (int i = 0; i < N; i++) {
                if (small > Math.abs(L + i)) {
                    small = Math.abs(L + i);
                    small_noneabs = L + i;
                }
                ttl += L + i;
            }
            out.println(ttl - small_noneabs);

        }

    }
}

