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

// macros
#define pb emplace_back
#define mk make_pair
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n) FOR(i, 0, n)
#define rrep(i, n) for(int i=((int)(n)-1);i>=0;i--)
#define irep(itr, st) for(auto itr = (st).begin(); itr != (st).end(); ++itr)
#define irrep(itr, st) for(auto itr = (st).rbegin(); itr != (st).rend(); ++itr)
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end())
#define bit(n) (1LL<<(n))
// functions
template <class T>bool chmax(T &a, const T &b){if(a < b){a = b; return 1;} return 0;}
template <class T>bool chmin(T &a, const T &b){if(a > b){a = b; return 1;} return 0;}
template <typename T> istream &operator>>(istream &is, vector<T> &vec){for(auto &v: vec)is >> v; return is;}
template <typename T> ostream &operator<<(ostream &os, const vector<T>& vec){for(int i = 0; i < vec.size(); i++){ os << vec[i]; if(i + 1 != vec.size())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_set<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T> ostream &operator<<(ostream &os, const unordered_multiset<T>& st){for(auto itr = st.begin(); itr != st.end(); ++itr){ os << *itr; auto titr = itr; if(++titr != st.end())os << " ";} return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &p){os << p.first << " " << p.second; return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
template <typename T1, typename T2> ostream &operator<<(ostream &os, const unordered_map<T1, T2> &mp){for(auto itr = mp.begin(); itr != mp.end(); ++itr){ os << itr->first << ":" << itr->second; auto titr = itr; if(++titr != mp.end())os << " "; } return os;}
//  types
using ll = long long int;
using P = pair<int, int>;
// constants
const int inf = 1e9;
const ll linf = 1LL << 50;
const double EPS = 1e-10;
const int mod = 1000000007;
const int dx[4] = {-1, 0, 1, 0};
const int dy[4] = {0, -1, 0, 1};
// io
struct fast_io{
  fast_io(){ios_base::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(20);}
} fast_io_;

template <typename T>
struct MergableRangeSet{
  using PT = pair<T, T>;
  set<PT> st;
  MergableRangeSet(){}
  // [l, r)
  void add(T l, T r){
    if(r <= l)return;
    auto itr = st.upper_bound(make_pair(l, 0));
    if(itr != st.begin()){
      auto litr = itr;
      --litr;
      if(litr->second >= r){
        return;
      }else if(litr->second >= l){
        l = litr->first;
        st.erase(litr);
      }
    }
    if(itr != st.end()){
      if(r < itr->first)st.insert(make_pair(l, r));
      else {
        PT p = make_pair(l, max(r, itr->second));
        st.erase(itr);
        st.insert(p);
      }
    }else{
      st.insert(make_pair(l, r));
    }
  }
  typename set<PT>::iterator begin() noexcept{
    return st.begin();
  }
  typename set<PT>::iterator end() noexcept{
    return st.end();
  }
  size_t size(){
    return st.size();
  }
};

map<ll, MergableRangeSet<ll>> ms;

int main(int argc, char const* argv[])
{
  int n; cin >> n;
  ll x, d; cin >> x >> d;
  if(d == 0){
    set<ll> st;
    rep(i, n + 1)st.insert((ll)i * x);
    cout << sz(st) << endl;
    return 0;
  }
  rep(i, n + 1){
    ll b = ((ll)i * x) % d;
    ll of = ((ll)i * x) / d;
    if(ms.find(b) == ms.end())ms[b] = MergableRangeSet<ll>();
    ll l = (ll)(i - 1) * (ll)i / 2;
    ll r = l + (ll)(i) * (ll)(n - i);
    ms[b].add(l + of, r + of + 1);
  }
  ll res = 0;
  irep(itr, ms){
    auto& v = itr->second;
    irep(im, v){
      res += im->second - im->first;
    }
  }
  cout << res << endl;
  return 0;
}


Measured memory_bytes: 31488