#include <bits/stdc++.h>
#define GET_REP(_1, _2, _3, NAME, ...) NAME
#define rep(...) GET_REP(__VA_ARGS__, irep, _rep)(__VA_ARGS__)
#define rep1(...) GET_REP(__VA_ARGS__, irep1, _rep1)(__VA_ARGS__)
#define _rep(i, n) irep (i, 0, n)
#define _rep1(i, n) irep1(i, 1, n)
#define irep(i, a, n) for (int i = a; i < (int)(n); ++i)
#define irep1(i, a, n) for (int i = a; i <= (int)(n); ++i)
#define rrep(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define rrep1(i, n) for (int i = (int)(n); i >= 1; --i)
#define allrep(X, x) for (auto &&X : x)
#define all(x) begin(x), end(x)
#define debug(x) cout << #x " => " << (x) << endl
#ifdef LOCAL
  #include "../../Lib/cout_container.hpp"
#endif
using lint = long long;
constexpr int MOD = (int)1e9 + 7;
constexpr double EPS = 1e-9;
using namespace std;
namespace { struct INIT { INIT() { cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(15); } } INIT; }

template <bool merge_adjacent>
class SectionUnion {
  struct comp { bool operator()(const pair<long long, long long> &a, const pair<long long, long long> &b) const { return a.second < b.second; } };

  public:
  set<pair<long long, long long>, comp> section_set;
  SectionUnion(void) {}
  bool insert(long long l, long long r) {
    auto litr = section_set.lower_bound({0, l - merge_adjacent}), ritr = section_set.lower_bound({0, r});
    if (ritr != section_set.end() && r + merge_adjacent >= ritr->first) ++ritr;
    const bool exist = litr != ritr;
    if (exist) {
      l = min(l, litr->first), r = max(r, prev(ritr)->second);
      section_set.erase(litr, ritr);
    }
    section_set.insert({l, r});
    return exist;
  }
  bool remove(long long l, long long r, bool involve = false) {
    auto litr = section_set.lower_bound({0, l}), ritr = section_set.lower_bound({0, r});
    if (ritr != section_set.end() && r >= ritr->first) ++ritr;
    const bool exist = litr != ritr;
    if (exist) {
      long long ledge = litr->first, redge = prev(ritr)->second;
      section_set.erase(litr, ritr);
      if (!involve) {
        if (ledge < l) section_set.insert({ledge, l - 1});
        if (r < redge) section_set.insert({r + 1, redge});
      }
    }
    return exist;
  }
  bool same(long long a, long long b) const {
    if (b < a) swap(a, b);
    auto itr = section_set.lower_bound({0, b});
    return itr != section_set.end() && itr->first <= a;
  }
  pair<bool, pair<long long, long long>> get(long long x) const {
    auto itr = section_set.lower_bound({0, x});
    return {!(itr == section_set.end() && x < itr->first), *itr};
  }
  void clear(void) { section_set.clear(); }
  bool empty(void) const { return section_set.empty(); }
  int  size(void) const { return section_set.size(); }
};

int main(void) {
  lint n, x, d;
  cin >> n >> x >> d;
  if (d == 0) {
    if (x == 0) {
      cout << 1 << endl;
    } else {
      cout << n + 1 << endl;
    }
    return 0;
  }
  if (d < 0) {
    x = -x;
    d = -d;
  }
  unordered_map<int, SectionUnion<true>> now;
  for (lint A = 0; A <= n; ++A) {
    // S = Ax + Bd
    lint Bmin = (A - 1) * A / 2, Bmax = (2 * n - A - 1) * A / 2;
    lint Adiv = A * x / d, Smod = A * x % d;
    if (Smod < 0) {
      Smod += abs(d);
      ++Adiv;
    }
    now[Smod].insert(Adiv + Bmin, Adiv + Bmax);
  }
  lint cnt = 0;
  allrep (m, now) {
    allrep (p, m.second.section_set) cnt += p.second - p.first + 1;
  }
  cout << cnt << endl;
  return 0;
}

Measured memory_bytes: 30408