#include "bits/stdc++.h"
using namespace std;
#define ll long long
#define endl '\n'
#define rep(i, n) for(int i = 0; i < (int)(n); i++)
#define rep2(i,a,b) for(int i=int(a);i<int(b);i++)
#define pb emplace_back
#define all(x) (x).begin(),(x).end()
ll mod=1e9+7;
ll mod2=998244353;
const int INF=1e9;

signed main(){
   ll n,l;
   cin>>n>>l;
   ll ans=0;
   ll m=1e9;
   rep(i,n){
      ans+=l+i;
      if(abs(l+i)<abs(m))m=l+i;
   }
   cout<<ans-m<<endl;
}


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