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


public class Main {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    }

    private static int [] mergeTwoArrays(int [] a, int [] b) {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    }
}
class Point {
    private int value;
    private int index;
    public int getValue() {
        return value;
    }
    public int getIndex() {
        return index;
    }
    public Point(int value,int index) {
        this.value = value;
        this.index = index;
    }

}

class InputReader extends BufferedReader {
    StringTokenizer tokenizer;

    public InputReader(InputStream inputStream) {
        super(new InputStreamReader(inputStream), 32768);
    }

    public InputReader(String filename) {
        super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
        return tokenizer.nextToken();
    }

    public Integer nextInt() {
        return Integer.valueOf(next());
    }
    public Long nextLong() {return  Long.valueOf(next());}

    static class OutputWriter extends PrintWriter {
        public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        }

        public OutputWriter(Writer writer) {
            super(writer);
        }

        public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        }

        public void close() {
            super.close();
        }
    }
} import java.io.*; io.* java import java.util.*; util.* java public class Main {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    }

    private static int [] mergeTwoArrays(int [] a, int [] b) {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    }
} Main public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    } main {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    } InputStream inputStream = System.in; inputStream System.in System System.in OutputStream outputStream = System.out; outputStream System.out System System.out InputReader in = new InputReader(inputStream); in new InputReader(inputStream) InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream); out new InputReader.OutputWriter(outputStream) int n = in.nextInt(); n in.nextInt() in.nextInt in int l = in.nextInt(); l in.nextInt() in.nextInt in int [] a = new int[n]; a new int[n] n for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            a[i] = l + i;
        } {
            a[i] = l + i;
        } a[i] = l + i a[i] a i l + i l i int min = Integer.MAX_VALUE; min Integer.MAX_VALUE Integer Integer.MAX_VALUE for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        } {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        } if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            } Math.abs(a[i]) < Math.abs(min) Math.abs(a[i]) Math.abs Math a[i] a i Math.abs(min) Math.abs Math min {
                min = a[i];
            } min = a[i] min a[i] a i int sum = 0; sum 0 for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        } int i = 0; int i = 0; i 0 i < a.length i a.length a a.length i++ i++ i {
            if(a[i]!=min) {
                sum+=a[i];
            }
        } {
            if(a[i]!=min) {
                sum+=a[i];
            }
        } if(a[i]!=min) {
                sum+=a[i];
            } a[i]!=min a[i] a i min {
                sum+=a[i];
            } sum+=a[i] sum a[i] a i out.println(sum) out.println out sum out.flush() out.flush out String[] args args private static int [] mergeTwoArrays(int [] a, int [] b) {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    } mergeTwoArrays {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    } int [] res = new int[a.length + b.length]; res new int[a.length + b.length] a.length + b.length a.length a a.length b.length b b.length int i = 0; i 0 int j = 0; j 0 int index = 0; index 0 while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        } i<a.length && j<b.length i<a.length i a.length a a.length j<b.length j b.length b b.length {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        } if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            } a[i]<b[j] a[i] a i b[j] b j {
                res[index++] = a[i++];
            } res[index++] = a[i++] res[index++] res index++ index a[i++] a i++ i {
                res[index++] = b[j++];
            } res[index++] = b[j++] res[index++] res index++ index b[j++] b j++ j System.out.println(i + " " + j) System.out.println System.out System System.out i + " " + j i + " " + j i " " j if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        } j == b.length - 1 j b.length - 1 b.length b b.length 1 {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        } while (i<a.length) {
                res[index++] = a[i++];
            } i<a.length i a.length a a.length {
                res[index++] = a[i++];
            } res[index++] = a[i++] res[index++] res index++ index a[i++] a i++ i {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        } while (j<b.length) {
                res[index++] = b[j++];
            } j<b.length j b.length b b.length {
                res[index++] = b[j++];
            } res[index++] = b[j++] res[index++] res index++ index b[j++] b j++ j return res; res int [] a a int [] b b class Point {
    private int value;
    private int index;
    public int getValue() {
        return value;
    }
    public int getIndex() {
        return index;
    }
    public Point(int value,int index) {
        this.value = value;
        this.index = index;
    }

} Point private int value; value private int index; index public int getValue() {
        return value;
    } getValue {
        return value;
    } return value; value public int getIndex() {
        return index;
    } getIndex {
        return index;
    } return index; index public Point(int value,int index) {
        this.value = value;
        this.index = index;
    } Point {
        this.value = value;
        this.index = index;
    } this.value = value this.value this this.value value this.index = index this.index this this.index index int value value int index index class InputReader extends BufferedReader {
    StringTokenizer tokenizer;

    public InputReader(InputStream inputStream) {
        super(new InputStreamReader(inputStream), 32768);
    }

    public InputReader(String filename) {
        super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
        return tokenizer.nextToken();
    }

    public Integer nextInt() {
        return Integer.valueOf(next());
    }
    public Long nextLong() {return  Long.valueOf(next());}

    static class OutputWriter extends PrintWriter {
        public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        }

        public OutputWriter(Writer writer) {
            super(writer);
        }

        public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        }

        public void close() {
            super.close();
        }
    }
} InputReader StringTokenizer tokenizer; tokenizer public InputReader(InputStream inputStream) {
        super(new InputStreamReader(inputStream), 32768);
    } InputReader {
        super(new InputStreamReader(inputStream), 32768);
    } super(new InputStreamReader(inputStream), 32768) super new InputStreamReader(inputStream) 32768 InputStream inputStream inputStream public InputReader(String filename) {
        super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
    } InputReader {
        super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
    } super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename))) super new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)) String filename filename public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
        return tokenizer.nextToken();
    } next {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
        return tokenizer.nextToken();
    } while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        } tokenizer == null || !tokenizer.hasMoreTokens() tokenizer == null tokenizer null !tokenizer.hasMoreTokens() tokenizer.hasMoreTokens() tokenizer.hasMoreTokens tokenizer {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        } try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            } catch (IOException e) {
                throw new RuntimeException();
            } IOException e {
                throw new RuntimeException();
            } throw new RuntimeException(); new RuntimeException() {
                tokenizer = new StringTokenizer(readLine());
            } tokenizer = new StringTokenizer(readLine()) tokenizer new StringTokenizer(readLine()) return tokenizer.nextToken(); tokenizer.nextToken() tokenizer.nextToken tokenizer public Integer nextInt() {
        return Integer.valueOf(next());
    } nextInt {
        return Integer.valueOf(next());
    } return Integer.valueOf(next()); Integer.valueOf(next()) Integer.valueOf Integer next() next public Long nextLong() {return  Long.valueOf(next());} nextLong {return  Long.valueOf(next());} return  Long.valueOf(next()); Long.valueOf(next()) Long.valueOf Long next() next static class OutputWriter extends PrintWriter {
        public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        }

        public OutputWriter(Writer writer) {
            super(writer);
        }

        public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        }

        public void close() {
            super.close();
        }
    } OutputWriter public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        } OutputWriter {
            super(outputStream);
        } super(outputStream) super outputStream OutputStream outputStream outputStream public OutputWriter(Writer writer) {
            super(writer);
        } OutputWriter {
            super(writer);
        } super(writer) super writer Writer writer writer public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        } OutputWriter {
            super(filename);
        } super(filename) super filename String filename filename public void close() {
            super.close();
        } close {
            super.close();
        } super.close() super.close super PrintWriter BufferedReader public class Main {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    }

    private static int [] mergeTwoArrays(int [] a, int [] b) {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    }
} public class Main {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    }

    private static int [] mergeTwoArrays(int [] a, int [] b) {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    }
} Main
import java.io.*;
import java.util.*;


public class Main {

    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        InputReader.OutputWriter out = new InputReader.OutputWriter(outputStream);

        int n = in.nextInt();
        int l = in.nextInt();
        int [] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = l + i;
        }
        
        int min = Integer.MAX_VALUE;
        for (int i = 0; i < a.length; i++) {
            if(Math.abs(a[i]) < Math.abs(min)) {
                min = a[i];
            }
        }
        int sum = 0;
        for (int i = 0; i < a.length; i++) {
            if(a[i]!=min) {
                sum+=a[i];
            }
        }
        out.println(sum);
        out.flush();
    }

    private static int [] mergeTwoArrays(int [] a, int [] b) {
        int [] res = new int[a.length + b.length];
        int i = 0;
        int j = 0;
        int index = 0;
        while (i<a.length && j<b.length) {
            if(a[i]<b[j]) {
                res[index++] = a[i++];
            }
            else {
                res[index++] = b[j++];
            }
        }
        System.out.println(i + " " + j);
        if(j == b.length - 1) {
            while (i<a.length) {
                res[index++] = a[i++];
            }
        }
        else {
            while (j<b.length) {
                res[index++] = b[j++];
            }
        }
        return res;
    }
}
class Point {
    private int value;
    private int index;
    public int getValue() {
        return value;
    }
    public int getIndex() {
        return index;
    }
    public Point(int value,int index) {
        this.value = value;
        this.index = index;
    }

}

class InputReader extends BufferedReader {
    StringTokenizer tokenizer;

    public InputReader(InputStream inputStream) {
        super(new InputStreamReader(inputStream), 32768);
    }

    public InputReader(String filename) {
        super(new InputStreamReader(Thread.currentThread().getContextClassLoader().getResourceAsStream(filename)));
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(readLine());
            } catch (IOException e) {
                throw new RuntimeException();
            }
        }
        return tokenizer.nextToken();
    }

    public Integer nextInt() {
        return Integer.valueOf(next());
    }
    public Long nextLong() {return  Long.valueOf(next());}

    static class OutputWriter extends PrintWriter {
        public OutputWriter(OutputStream outputStream) {
            super(outputStream);
        }

        public OutputWriter(Writer writer) {
            super(writer);
        }

        public OutputWriter(String filename) throws FileNotFoundException {
            super(filename);
        }

        public void close() {
            super.close();
        }
    }
}