#include<bits/stdc++.h>

using namespace std;


int main(){
  int N, L;
  cin >> N >> L;
  
  int eated_apple = 10000000;
  int sum_taste = 0;
  for(int i=1; i<=N; i++){
    sum_taste += L+i-1;
    if(abs(eated_apple)>abs(L+i-1)) eated_apple = L+i-1;
  }
  
  cout << sum_taste-eated_apple << endl;
  
  return 0;
}
#include <bits/stdc++.h>
using namespace std;
///////////////////////////////////////////
const long long int INF = 1LL<<60;
const long long int Mod = 1000000007;
const long long int sMod = 998244353;
using ll = long long int; using ci = const int;
using vi = vector<int>;  using Vi = vector<long long int>;
using P = pair<int, int>;  using PLL = pair<ll, ll>;
using matrix = vector<vector<ll>>;
#define pb(x) push_back(x)
#define mp(x,y) make_pair(x,y)
#define fi first
#define se second
#define all(x) (x).begin(),(x).end()
#define rp(i,N) for(ll i = 0; i < (ll)N; i++)
#define repi(i,a,b) for(ll i = ll(a); i < ll(b); ++i)
template<class T>bool chmax(T &former, const T &b) { if (former<b) { former=b; return true; } return false; }
template<class T>bool chmin(T &former, const T &b) { if (b<former) { former=b; return true; } return false; }
template<class T>T sqar(T x){ return x*x; }//sqrt(x)は平方根;
#define Sort(v) std::sort(v.begin(), v.end(), std::greater<decltype(v[0])>()) //降順でVをソート
#define p_queue(v) priority_queue<v, vector<v>, greater<v> >
template<class T> inline void princ(T x){cout<<x<<" ";}; 
template<class T> inline void print(T x){cout<<x<<"\n";};
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
///////////////////////////////////////////////////////////////////////////////////

void solve(){
    ll n;
    ll l;
    cin >> n >> l;
    if(l>=0) print((l+l+n-1)*n/2-l);
    else if(l+n-1>=0) print((l+l+n-1)*n/2);
    else print((l+l+n-1)*n/2-(l+n-1));
    return;
}
int main(){
    cin.tie(0);ios::sync_with_stdio(false);
    std::cout<<std::fixed<<std::setprecision(30);
    solve();
    return 0;
}