import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
long bignum = 1_000_000_007;

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

long manhattan(long x1, long y1, long x2, long y2)
{
    return abs(x2 - x1) + abs(y2 - y1);
}

void main()
{
    long n, l;
    scan(n, l);
    long sumf, minf = bignum;
    foreach (i; 0 .. n)
    {
        long f = l + i;
        minf = min(abs(minf), abs(f));
        sumf += f;
    }
    if (sumf >= 0)
        (sumf - minf).writeln();
    else
        (sumf + minf).writeln();
}
