#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <utility>
#include <tuple>
#include <cstdint>
#include <cstdio>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <deque>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <cctype>
#include <functional>
#include <ctime>
#include <cmath>
#include <limits>
#include <numeric>
#include <type_traits>
#include <iomanip>
#include <float.h>
#include <math.h>
using namespace std;
using ll = long long;
unsigned euclidean_gcd(unsigned a, unsigned b) {
    if (a < b) return euclidean_gcd(b, a);
    unsigned r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}

ll ll_gcd(ll a, ll b) {
    if (a < b) return ll_gcd(b, a);
    ll r;
    while ((r = a % b)) {
        a = b;
        b = r;
    }
    return b;
}

class UnionFind {
public:
    vector <ll> par;
    vector <ll> siz;
    UnionFind(ll sz_) : par(sz_), siz(sz_, 1LL) {
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    void init(ll sz_) {
        par.resize(sz_);
        siz.assign(sz_, 1LL);
        for (ll i = 0; i < sz_; ++i) par[i] = i;
    }
    ll root(ll x) {
        while (par[x] != x) {
            x = par[x] = par[par[x]];
        }
        return x;
    }
    bool merge(ll x, ll y) {
        x = root(x);
        y = root(y);
        if (x == y) return false;
        if (siz[x] < siz[y]) swap(x, y);
        siz[x] += siz[y];
        par[y] = x;
        return true;
    }

    bool issame(ll x, ll y) {
        return root(x) == root(y);
    }

    ll size(ll x) {
        return siz[root(x)];
    }
};

long long modpow(long long a, long long n, long long mod) {
    long long res = 1;
    while (n > 0) {
        if (n & 1) res = res * a % mod;
        a = a * a % mod;
        n >>= 1;
    }
    return res;
}

long long modinv(long long a, long long mod) {
    return modpow(a, mod - 2, mod);
}

int main() {
    ll n,x,d;
    cin >> n >> x >> d;
    if (d == 0&&x==0) {
        cout << 1 << endl;
    }
    else if (d == 0) {
        cout << n+1 << endl;
    }
    else if (x == 0) {
        cout << n * (n - 1)/2 + 1 << endl;
    }
    else {

        x *= d / abs(d);
        d = abs(d);
        ll g = 0;
        if (x != 0)g = ll_gcd(abs(x), d);
        else g = d;
        d /= g;
        x /= g;
        vector<ll> mn(n+1);
        ll now = x;
        for (int i = 0; i < n; i++) {
            if (i != 0)mn[i+1] += mn[i];
            mn[i+1] += now;
            now += d;
        }
        ll ans = 0;
        for (int i = 0; i < min(n+2, d); i++) {
            vector<pair<ll,ll>> z;
            for (int j = 0; j < 1000000; j++) {
                if (j * d + i > n)break;
                ll mns = mn[j * d + i];
                ll mxs = mn[n] - mn[n - (j * d + i)];
                z.push_back(make_pair(mns, mxs));
            }
            sort(z.begin(), z.end());
            ll c = -123456789015234567+d;
            ll k = -123456789015234567;
            for (int j = 0; j < z.size(); j++) {
                if (k < z[j].first) {
                    ans+=(k - (c - d)) / d;
                    c = z[j].first;
                    k = z[j].second;
                }
                else {
                    k = max(k,z[j].second);
                }
            }
            ans += (k - (c - d)) / d;
        }
        cout << ans << endl;
    }
}

Measured memory_bytes: 9000