#include <bits/stdc++.h>

#define rep(i, n) for (int i = 0; i < int(n); i++)
#define rrep(i, n) for (int i = int(n) - 1; i >= 0; i--)
#define reps(i, n) for (int i = 1; i <= int(n); i++)
#define rreps(i, n) for (int i = int(n); i >= 1; i--)
#define repc(i, n) for (int i = 0; i <= int(n); i++)
#define rrepc(i, n) for (int i = int(n); i >= 0; i--)
#define repi(i, a, b) for (int i = int(a); i < int(b); i++)
#define repic(i, a, b) for (int i = int(a); i <= int(b); i++)
#define each(x, y) for (auto &x : y)
#define all(a) (a).begin(), (a).end()
#define bit32(x) (1 << (x))
#define bit64(x) (1ll << (x))

using namespace std;

using i32 = int;
using i64 = long long;
using u64 = unsigned long long;
using f80 = long double;
using vi32 = vector<i32>;
using vi64 = vector<i64>;
using vu64 = vector<u64>;
using vf80 = vector<f80>;
using vstr = vector<string>;
using vp64 = vector<pair<i64, i64>>;

inline void yes() { cout << "Yes" << '\n'; exit(0); }
inline void no() { cout << "No" << '\n'; exit(0); }
inline i64 gcd(i64 a, i64 b) { if (min(a, b) == 0) return max(a, b); if (a % b == 0) return b; return gcd(b, a % b); }
inline i64 lcm(i64 a, i64 b) { return a / gcd(a, b) * b; }
inline u64 xorshift() { static u64 x = 88172645463325252ull; x = x ^ (x << 7); return x = x ^ (x >> 9); }
template <typename T> class pqasc : public priority_queue<T, vector<T>, greater<T>> {};
template <typename T> class pqdesc : public priority_queue<T, vector<T>, less<T>> {};
template <typename T> inline void amax(T &x, T y) { if (x < y) x = y; }
template <typename T> inline void amin(T &x, T y) { if (x > y) x = y; }
template <typename T> inline T exp(T x, i64 n, T e = 1) { T r = e; while (n > 0) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; }
template <typename T> inline T bis(T ok, T ng, function<bool(T)> f, T eps = 1) { while (abs(ok - ng) > eps) { T mi = (ok + ng) / 2; (f(mi) ? ok : ng) = mi; } return ok; }
template <typename T> istream& operator>>(istream &is, vector<T> &v) { each(x, v) is >> x; return is; }
template <typename T> ostream& operator<<(ostream &os, vector<T> &v) { rep(i, v.size()) { if (i) os << ' '; os << v[i]; } return os; }
void solve(); int main() { ios::sync_with_stdio(0); cin.tie(0); cout << fixed << setprecision(16); solve(); return 0; }

void solve() {
  i64 n, x, d;
  cin >> n >> x >> d;
  if (d == 0) {
    unordered_set<i64> se;
    repc(i, n) {
      int j = n - i;
      se.insert(x * i - x * j);
    }
    cout << se.size() << endl;
    return;
  }
  unordered_map<i64, vp64> mp;
  for (i64 k = 0; k <= n; k++) {
    i64 key = (x * k) % d;
    if (key < 0) key += abs(d);

    i64 mi = x * k + (k * (k - 1) / 2) * d;
    i64 ma = x * k + (n * k - k * (k + 1) / 2) * d;
    if (mi > ma) swap(mi, ma);

    mp[key].emplace_back(mi, 1);
    mp[key].emplace_back(ma, 2);
  }
  i64 ans = 0;
  each(m, mp) {
    auto &ve = m.second;
    sort(all(ve));
    int cnt = 0;
    i64 begin;
    each(v, ve) {
      i64 va, ev;
      tie(va, ev) = v;
      if (ev == 1) {
        if (cnt == 0) {
          begin = va;
        }
        cnt++;
      } else if (ev == 2) {
        cnt--;
        if (cnt == 0) {
          ans += (va - begin) / abs(d) + 1;
        }
      }
    }
  }
  cout << ans << endl;
}


Measured memory_bytes: 21064