#include <bits/stdc++.h>
using namespace std;

//type
#define ll long long
typedef pair<int, int> P;
//定数
#define INF 1000000000000 //10^12:∞
#define MOD 1000000007    //10^9+7:合同式の法
#define MAXR 100000       //10^5:配列の最大のrange
//略記
#define PB push_back //挿入
#define MP make_pair //pairのコンストラクタ
#define F first      //pairの一つ目の要素
#define S second     //pairの二つ目の要素
#define Z class

// input
#define INIT                          \
    std::ios::sync_with_stdio(false); \
    std::cin.tie(0);
#define VAR(type, ...) \
    type __VA_ARGS__;  \
    MACRO_VAR_Scan(__VA_ARGS__);
template <typename T>
void MACRO_VAR_Scan(T &t)
{
    std::cin >> t;
}
template <typename First, typename... Rest>
void MACRO_VAR_Scan(First &first, Rest &... rest)
{
    std::cin >> first;
    MACRO_VAR_Scan(rest...);
}
#define VEC_ROW(type, n, ...)                \
    std::vector<type> __VA_ARGS__;           \
    MACRO_VEC_ROW_Init(n, __VA_ARGS__);      \
    for (int w_ = 0; w_ < n; ++w_)           \
    {                                        \
        MACRO_VEC_ROW_Scan(w_, __VA_ARGS__); \
    }
template <typename T>
void MACRO_VEC_ROW_Init(int n, T &t)
{
    t.resize(n);
}
template <typename First, typename... Rest>
void MACRO_VEC_ROW_Init(int n, First &first, Rest &... rest)
{
    first.resize(n);
    MACRO_VEC_ROW_Init(n, rest...);
}
template <typename T>
void MACRO_VEC_ROW_Scan(int p, T &t) { std::cin >> t[p]; }
template <typename First, typename... Rest>
void MACRO_VEC_ROW_Scan(int p, First &first, Rest &... rest)
{
    std::cin >> first[p];
    MACRO_VEC_ROW_Scan(p, rest...);
}
#define VEC(type, c, n)     \
    std::vector<type> c(n); \
    for (auto &i : c)       \
        std::cin >> i;
// 2d vector:  MAT(type, v, size, size);
#define MAT(type, c, m, n)                                     \
    std::vector<std::vector<type>> c(m, std::vector<type>(n)); \
    for (auto &R : c)                                          \
        for (auto &w : R)                                      \
            std::cin >> w;

// output
template <typename T>
void MACRO_OUT(const T t) { std::cout << t; }

#define OUT(...) MACRO_OUT(__VA_ARGS__);
#define SP std::cout << " ";
#define TAB std::cout << "\t";
#define BR std::cout << "\n";
#define ENDL std::cout << std::endl;

#define YES() printf("YES\n")
#define NO() printf("NO\n")
#define isYES(x) printf("%s\n", (x) ? "YES" : "NO")
#define Yes() printf("Yes\n")
#define No() printf("No\n")
#define yes() printf("yes\n")
#define no() printf("no\n")
#define ln cout << '\n'
template <Z A>
void pr(A a)
{
    cout << a;
    ln;
}
template <Z A, Z B>
void pr(A a, B b)
{
    cout << a << ' ' << b << endl;
}

// OTHER
// xの二乗を返す (関数テンプレート版)
template <typename T>
T square(T x) { return x * x; }
template <class T>
T GCD(T a, T b)
{
    T r;
    while (a)
        r = b, b = a, a = r % a;
    return b;
}
template <class T>
T LCM(T a, T b) { return a / GCD(a, b) * b; }

#define chmax(x, y) (x = max(x, y))
#define chmin(x, y) (x = min(x, y))
// loop
#define rep(i, n) for (ll i = 0; i < (n); i++)
#define repe(i, n) for (ll i = 0; i <= (n); i++)
#define repd(i, n) for (ll i = n; i > 0; i--)
#define repde(i, n) for (ll i = n; i >= 0; i--)
#define FOR(i, a, b) for (ll i = a; i < (b); i++)
#define FORE(i, a, b) for (ll i = a; i <= (b); i++)
#define FORD(i, a, b) for (ll i = a; i >= (b); i--)
#define FORA(i, I) for (const auto &i : I)

// vector
#define ALL(x) x.begin(), x.end()
typedef vector<int> vi;
typedef vector<string> vs;
typedef vector<vi> vvi;
typedef vector<ll> vl;
#define ERASE(x) x.erase(unique(ALL(x)), x.end()); // erase same elements

bool yes = 0;
bool boo = 0;
int maxx = -100000, minn = 100000;
int sum = 0;
int ans = 0;
int co = 0;

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
// cout << (conditon ? (result:  == 1 ): (==0)) << endl; <- output result of if
// long long 型が表せる値の上限はおよそ 9 × 10＾18 です．

// vector
// sum: accumulate(ALl(x),0)
signed main()
{
    // abc 131 b
    // 最もおいしさの絶対値の小さいりんごを食べるのが、最適なので、
    //そのりんごを除いた全てのりんごのおいしさの和を出力すればいい

    VAR(int, n, a);
    int l = a;
    int r = a + n - 1;
    int eat;
    if (r <= 0)
        eat = r;
    else if (l >= 0)
        eat = l;
    else
        eat = 0;
    ans = (r + l) * (r - l + 1) / 2 - eat;
    pr(ans);

    return 0;
}

Measured memory_bytes: 3620