#include <bits/stdc++.h>
using namespace std;
const long long MOD = 1e9 + 7;
const long long MX = 1e10 + 10;;
unsigned long long fac[200001];

#include <math.h>
#define PI 3.14159265358979323846264338327950L

long long gcd(long long a, long long b) {
    if (a == 0)
        return b;
    return gcd(b % a, a);
}
long long lcm(long long a, long long b) {
    return (a * b) / gcd(a, b);
}
long long digits(long long m) {
    long long cnt = 0;
    while (m) {
        cnt++;
        m /= 10;
    }
    return cnt;
}

unsigned long long power(unsigned long long x, unsigned long long y){
    unsigned long long res = 1;
    x = x % MOD;

    while (y > 0) {
        // If y is odd, multiply x with result 
        if (y & 1)
            res = (res * x) % MOD;

        // y must be even now 
        y = y >> 1; // y = y/2 
        x = (x * x) % MOD;
    }
    return res;
}
unsigned long long modInverse(unsigned long long n) {
    return power(n, MOD - 2);
}

long long nCr(long long n, long long r) {
    if (r > n) return 0;
    return (fac[n] * modInverse(fac[r]) % MOD * modInverse(fac[n - r]) % MOD) % MOD;
}

long long bfs(vector<int> g, queue<int> q) {
    return 1ll;
}

int main() {

    int n, l;
    cin >> n >> l;
    vector<int> a(n);
    long long sum = 0;
    for (int i = 0; i < n; i++) {
        a[i] = l + i;
        sum += a[i];
    }
    int mn = 999999;
    int pos = -1;
    for (int i = 0; i < n; i++) {
        if (abs(a[i]) < mn) {
            mn = abs(a[i]);
            pos = i;
        }
    }
    sum -= a[pos];
    cout << sum;
    return 0;
}
#include <bits/stdc++.h>
using namespace std;

#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 
using namespace __gnu_pbds; 
  
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> 
 
#define FS              ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define ll              long long int
#define ld              long double
#define pb              push_back
#define bp              __builtin_popcount
#define sz              size()
#define ff              first
#define ss              second
#define vll             vector<ll>
#define vbool           vector<bool>
#define vpll            vector<pair<ll,ll>>
#define pll             pair<ll,ll>
#define vllv            vector<vector<ll>>
#define setpri(x)       cout<<setprecision(x)<<fixed;
#define all(v)          v.begin(),v.end()
#define allr(v)         v.rbegin(),v.rend()
#define yesr {cout<<"YES"<<endl;return;}
#define nor {cout<<"NO"<<endl;return;}
// getline (std::cin,name);
ll MOD=1e9+7;
ll ceil1(ll n,ll x){return (n-1)/x+(n>0);}

ll gcd(ll a,ll b){return __gcd(a,b);}
ll lcm(ll a,ll b){return (max(a,b)/gcd(a,b))*min(a,b);}

ll pow1(ll n,ll m ,ll mod=MOD );
ll pow2(ll n,ll k);

ll modinv(ll n,ll mod=MOD){  return pow1(n,mod-2,mod);}

bool func(pair<ll,ll> &a,pair<ll,ll> &b ){
        if(a.ff != b.ff)return a.ff < b.ff;
        return a.ss > b.ss;
}
ll const N=(ll)3e2+11;
ll const LG=(ll)log2(N)+1;


void solve(){
        ll i,j,k,l,n,m,x,y,z,r;
        
        cin>>n>>l;
        ll tt=0;
        for(i=1;i<=n;i++){
                tt+=l+i-1;
        }
        if(n==1){
                cout<<0<<endl;
                return;
        }
        ll ans=-100000;
        for(i=1;i<=n;i++){
                ll t1=tt-l+1-i;
                if(abs(t1-tt)<abs(tt-ans)){
                        ans=t1;
                }
        }
        cout<<ans<<endl;
        
}       
int main(){
        FS;
        
        ll i,j,k,n,m,x,y,z,q;
        q=1;
        // cin>>q;
        while(q--){
                solve();
        }
        return 0;
}


ll pow1(ll n,ll m,ll mod){
        if(m==0)return 1;
        
        if(m%2==0)return pow1((n*n)%mod,m/2,mod);
    	
    	return (pow1((n*n)%mod,m/2,mod)*n)%mod;
}

ll pow2(ll n,ll k){
        ll ans=1;
            while(k>0){
                if(k%2==1)ans=ans*n;
                n=n*n;
                k/=2;
            }
            return ans;
}