#include <bits/stdc++.h>

#include <unistd.h>
 
using namespace std;
 
#define DEBUG(x) cerr<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cerr<<#v<<":";for(int i=0;i<v.size();i++) cerr<<" "<<v[i]; cerr<<endl
#define DEBUG_MAT(v) cerr<<#v<<endl;for(int i=0;i<v.size();i++){for(int j=0;j<v[i].size();j++) {cerr<<v[i][j]<<" ";}cerr<<endl;}
 
 
typedef long long ll;
#define int ll
 
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
template<class S, class T> pair<S, T> operator+(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first + t.first, s.second + t.second); }
template<class S, class T> pair<S, T> operator-(const pair<S, T> &s, const pair<S, T> &t) { return pair<S, T>(s.first - t.first, s.second - t.second); }
template<class S, class T> ostream& operator<<(ostream& os, pair<S, T> p) { os << "(" << p.first << ", " << p.second << ")"; return os; }
#define X first
#define Y second
#define rep(i,n) for(int i=0;i<(n);i++)
#define rep1(i,n) for(int i=1;i<=(n);i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define rrep1(i,n) for(int i=(n);i>0;i--)
#define REP(i,a,b) for(int i=a;i<b;i++)
#define in(x, a, b) (a <= x && x < b)
#define all(c) c.begin(),c.end()
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; }
#define UNIQUE(v) v.erase(std::unique(v.begin(), v.end()), v.end());
const ll inf = 1000000001;
const ll INF = (ll)1e18 + 1;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx_ori[4] = { -1,0, 1,0 }, dy_ori[4] = { 0,1,0,-1 };
int dx[4] = {0, 0, 0, 0}, dy[4] = {0, 0, 0, 0};
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };
#define fio() cin.tie(0); ios::sync_with_stdio(false);
const ll MOD = 1000000007;
//const ll MOD = 998244353;
// #define mp make_pair
//#define endl '\n'

void convert(ll n, ll &x, ll &d) {
  if (d > 0) return;
  ll y = x + (n - 1) * d;
  x = y;
  d = -d;
}

pll merge2(pll a, pll b) {
  return pll(min(a.first, b.first), max(a.second, b.second));
}

vector<pll> merge(vector<pll> lr) {
  sort(all(lr));
  reverse(all(lr));
  vector<pll> res;
  while (lr.size() > 0) {
    if (res.size() == 0) {
      res.push_back(lr.back());
      lr.pop_back();
      continue;
    }
    pll temp = lr.back();
    lr.pop_back();
    if (res.back().second < temp.first) {
      res.push_back(temp);
      continue;
    }
    pll p = res.back();
    res.pop_back();
    p = merge2(p, temp);
    res.push_back(p);
  }
  return res;
}

signed main() {
  ll n, x, d;
  cin >> n >> x >> d;
  if (d == 0) {
    if (x != 0) {
      cout << n + 1 << endl;
    }
    else {
      cout << 1 << endl;
    }
    return 0;
  }
  convert(n, x, d);

  map<ll, vl> mod2k;
  rep (k, n + 1) {
    ll m = k * x % d;
    mod2k[m].push_back(k);
  }

  ll ans = 0;
  for (auto itr = mod2k.begin(); itr != mod2k.end(); itr++) {
    vl ks = itr->second;
    sort(all(ks));
    vector<pll> lr;
    ll m = itr->first;
    for (ll k: ks) {
      assert((k * x - m) % d == 0);
      ll mi = (k * x - m) / d + (k - 1) * k / 2;
      ll ma = (k * x - m) / d + ((n - 1) * n / 2 - (n - k - 1) * (n - k) / 2);
      ma++;
      lr.push_back(pll(mi, ma));
      //DEBUG_VEC(lr);
    }
    lr = merge(lr);
    rep (i, lr.size()) {
      ans += (lr[i].second - lr[i].first);
    }
  }
  cout << ans << endl;
}


Measured memory_bytes: 22144