#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define F first
#define S second
#define pii pair<int, int>
#define pli pair<ll, int>
#define pil pair<int, ll>
#define pll pair<ll, ll>
#define eb emplace_back
#define all(v) v.begin(), v.end()
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep3(i, l, n) for (int i = l; i < (n); ++i)
#define sz(v) (int)v.size()
#define endl '\n'
const int inf = 1000000007;
const ll INF = 1e18;
// int mod = 998244353;
int mod = 1000000007;
#define abs(x) (x >= 0 ? x : -(x))
#define lb(v, x) (int)(lower_bound(all(v), x) - v.begin())
#define ub(v, x) (int)(upper_bound(all(v), x) - v.begin())
template<typename T1, typename T2> inline bool chmin(T1 &a, T2 b) { if (a > b) { a = b; return 1; } return 0; }
template<typename T1, typename T2> inline bool chmax(T1 &a, T2 b) { if (a < b) { a = b; return 1; } return 0; }
ll gcd(ll a, ll b) { if (b == 0) return a; return gcd(b, a % b); }
ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }
template<typename T, typename U> T pow_(T a, U b) { return b ? pow_(a * a, b / 2) * (b % 2 ? a : 1) : 1; }
ll modpow(ll a, ll b, ll _mod) { return b ? modpow(a * a % _mod, b / 2, _mod) * (b % 2 ? a : 1) % _mod : 1; }
template<class T, class U> ostream& operator << (ostream& os, const pair<T, U>& p) { os << p.F << " " << p.S; return os; }
template<class T> ostream& operator << (ostream& os, const vector<T>& vec) { rep(i, sz(vec)) { if (i) os << " "; os << vec[i]; } return os; }
template<typename T> inline istream& operator >> (istream& is, vector<T>& v) { rep(j, sz(v)) is >> v[j]; return is; }
template<class T, class T2> inline void add(T &a, T2 b) { a += b % mod; if (a >= mod) a -= mod; }
template<class T> void operator += (vector<T>& v, vector<T> v2) { rep(i, sz(v2)) v.eb(v2[i]); }

void solve();

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cout << fixed << setprecision(12); // debuged
    int T;
    T = 1;
    while (T--) solve();
}

// https://atcoder.jp/contests/abc147/submissions/15405003
void solve() {
    ll n, x, d;
    cin >> n >> x >> d;
    
    if (d == 0) { // 下で /d するから
        // Sが0個, -nx
        // Sが1個, x-(n-1)x = (2-n)x
        // Sが2個, 2x-(n-2)x = (4-n)x
        // ...
        // Sがn個, nx
        if (x == 0) cout << 1 << endl;
        else cout << n + 1 << endl;
        return;
    }
    
    
    // Tは, 変わらない総和Zを用いてZ-Sと表せる
    // S-T=2S-Z
    // Sが何通りあるか考えればいい
    map<ll, vector<pll> > mp; // dで割った余りごとに差を1で管理
    rep(k, n + 1) { // Sとしてとる個数
        // D*iのi
        // 0+1+...+(k-1) ~ (n-k)+...+(n-1)
        // 右に動かせるうち一番右のを1増やす
        ll rest = (k * x % d + d) % d;
        auto calc = [&](ll a, ll b) {
            ll ret = k * x + d * k * (a + b) / 2;
            ret = (ret - rest) / d;
            return ret;
        };
        ll l = calc(0, k - 1), r = calc(n - k, n - 1);
        mp[rest].eb(l, r);
        // cerr << rest << " " << k * x << " " << d * k * (k - 1) / 2 << " " << l << endl;
    }
    
    ll ans = 0;
    for (auto e : mp) {
        sort(all(e.S)); // debuged
        // d>0でも昇順じゃないことありうる
        // x<0なら, k=0でkx=0だが, k=1で負になる
        // 以降は昇順
        deque<pll> q;
        rep(i, sz(e.S)) q.emplace_back(e.S[i]);
        
        while (1) {
            pll a = q.front();
            q.pop_front();
            if (sz(q) == 0) {
                ans += a.S - a.F + 1;
                break;
            }
            pll b = q.front();
            q.pop_front();
            if (b.F <= a.S) { // merge
                q.emplace_front(a.F, max(a.S, b.S)); // debuged
            } else {
                ans += a.S - a.F + 1;
                q.emplace_front(b);
            }
        }
    }
    cout << ans << endl;
}




Measured memory_bytes: 25516