import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;

public class Main {

	private final static int MOD = 1000000007;

	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int L = sc.nextInt();

		int index;
		if (L >= 0) {
			index = 0;
		} else {
			index = Math.min(-L, N - 1);
		}

		int total = 0;
		for (int i = 0; i < N; i++) {
			if (i != index) {
				total += L + i;
			}
		}

		System.out.println(total);
	}

	private static class Key {
		private int sum;
		private int[] value;

		public Key(int[] value) {
			this.sum = (int) Arrays.stream(value).sum();
			this.value = value;
		}

		@Override
		public int hashCode() {
			return sum;
		}

		@Override
		public boolean equals(Object obj) {
			if (this == obj)
				return true;
			if (obj == null)
				return false;
			if (getClass() != obj.getClass())
				return false;

			Key other = (Key) obj;
			if (sum != other.sum)
				return false;
			if (!Arrays.equals(value, other.value))
				return false;
			return true;
		}
	}

	private static boolean isDebug = System.getProperty("sun.desktop") != null;

	private static void debug(Object... o) {
		if (isDebug) {
			System.err.println(Arrays.deepToString(o));
		}
	}

	private static int add(int a, int b) {
		return (a + b) % MOD;
	}

	private static int sub(int a, int b) {
		return (a - b % MOD) % MOD;
	}

	private static int mul(int a, int b) {
		return ((a % MOD) * (b % MOD)) % MOD;
	}

	public static class Scanner {
		private BufferedInputStream inputStream;
		private StringBuilder buffer = new StringBuilder();

		public Scanner(InputStream in) {
			inputStream = new BufferedInputStream(in);
		}

		public int nextInt() throws IOException {
			int num = 0;
			int sign = 1;

			int read = skip();
			if (read == '-') {
				sign = -1;
				read = inputStream.read();
			}

			do {
				num = num * 10 + sign * (read - 0x30);
			} while ((read = inputStream.read()) > 0x20);

			return num;
		}

		public void fill(int[] a) throws IOException {
			for (int i = 0; i < a.length; i++) {
				a[i] = nextInt();
			}
		}

		public void fill(int[] a, int[] b) throws IOException {
			if (a.length != b.length) {
				throw new IllegalArgumentException();
			}

			for (int i = 0; i < a.length; i++) {
				a[i] = nextInt();
				b[i] = nextInt();
			}
		}

		public long nextLong() throws IOException {
			long num = 0;
			int sign = 1;

			int read = skip();
			if (read == '-') {
				sign = -1;
				read = inputStream.read();
			}

			do {
				num = num * 10 + sign * (read - 0x30);
			} while ((read = inputStream.read()) > 0x20);

			return num;
		}

		public void fill(long[] a) throws IOException {
			for (int i = 0; i < a.length; i++) {
				a[i] = nextLong();
			}
		}

		public void fill(long[] a, long[] b) throws IOException {
			if (a.length != b.length) {
				throw new IllegalArgumentException();
			}

			for (int i = 0; i < a.length; i++) {
				a[i] = nextLong();
				b[i] = nextLong();
			}
		}

		public long[] nextLong(int n) throws IOException {
			long[] array = new long[n];
			for (int i = 0; i < n; i++) {
				array[i] = nextLong();
			}

			return array;
		}

		public String next() throws IOException {
			int read = skip();
			do {
				buffer.append((char) read);
			} while ((read = inputStream.read()) > 0x20);

			String text = buffer.toString();
			buffer.delete(0, buffer.length());

			return text;
		}

		private int skip() throws IOException {
			int read;
			while ((read = inputStream.read()) <= 0x20)
				;

			return read;
		}
	}
}


Measured memory_bytes: 22996