#include <bits/stdc++.h>
// created [2019/12/08] 21:23:47
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

using i32 = int32_t;
using i64 = int64_t;
using u32 = uint32_t;
using u64 = uint64_t;
using uint = unsigned int;
using usize = std::size_t;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
template<typename T> constexpr T popcount(const T u) { return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T log2p1(const T u) { return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template<typename T> constexpr T lsbp1(const T u) { return __builtin_ffsll(u); }
template<typename T> constexpr T clog(const T u) { return u ? log2p1(u - 1) : static_cast<T>(u); }
template<typename T> constexpr bool ispow2(const T u) { return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0; }
template<typename T> constexpr T ceil2(const T u) { return static_cast<T>(1) << clog(u); }
template<typename T> constexpr T floor2(const T u) { return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1); }
template<typename T> constexpr bool btest(const T mask, const usize ind) { return static_cast<bool>((static_cast<u64>(mask) >> ind) & static_cast<u64>(1)); }
template<typename T> void bset(T& mask, const usize ind) { mask |= (static_cast<T>(1) << ind); }
template<typename T> void breset(T& mask, const usize ind) { mask &= ~(static_cast<T>(1) << ind); }
template<typename T> void bflip(T& mask, const usize ind) { mask ^= (static_cast<T>(1) << ind); }
template<typename T> void bset(T& mask, const usize ind, const bool b) { (b ? bset(mask, ind) : breset(mask, ind)); }
template<typename T> constexpr T bcut(const T mask, const usize ind) { return ind == 0 ? static_cast<T>(0) : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >> (64 - ind)); }
template<typename T> bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template<typename T> bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
constexpr unsigned int mod                  = 1000000007;
template<typename T> constexpr T inf_v      = std::numeric_limits<T>::max() / 4;
template<typename Real> constexpr Real pi_v = Real{3.141592653589793238462643383279502884};

template<typename T>
T read()
{
    T v;
    return std::cin >> v, v;
}
template<typename T, typename... Args>
auto read(const usize size, Args... args)
{
    std::vector<decltype(read<T>(args...))> ans(size);
    for (usize i = 0; i < size; i++) { ans[i] = read<T>(args...); }
    return ans;
}
template<typename... Types>
auto reads() { return std::tuple<std::decay_t<Types>...>{read<Types>()...}; }
#    define SHOW(...) static_cast<void>(0)
constexpr ull TEN(const usize n) { return n == 0 ? 1ULL : TEN(n - 1) * 10ULL; }

template<typename T>
std::vector<T> make_v(const usize size, const T v) { return std::vector<T>(size, v); }
template<typename... Args>
auto make_v(const usize size, Args... args) { return std::vector<decltype(make_v(args...))>(size, make_v(args...)); }

template<typename Ind>
class ranges
{
public:
    static_assert(std::is_signed<Ind>::value, "Signed integer-type is required.");
    using size_type = Ind;
    ranges() : rs{{-inf_v<Ind>, -inf_v<Ind> + static_cast<Ind>(1)}, {inf_v<Ind> - static_cast<Ind>(1), inf_v<Ind>}} {}
    void insert(const size_type l, const size_type r)
    {
        auto lastit = rs.upper_bound(r);
        lastit--;
        auto firstit = lastit;
        for (; firstit->second >= l; firstit--) {}
        firstit++;
        const size_type lmin = std::min(firstit->first, l), rmax = std::max(lastit->second, r);
        rs.erase(firstit, std::next(lastit)), rs[lmin]           = rmax;
    }
    void erase(const size_type l, const size_type r)
    {
        auto lastit = rs.upper_bound(r);
        lastit--;
        auto firstit = lastit;
        for (; firstit->second >= l; firstit--) {}
        firstit++;
        const Ind left = firstit->first, right = lastit->second;
        rs.erase(firstit, std::next(lastit));
        if (left < l) { insert(left, l); }
        if (r < right) { insert(r, right); }
    }
    std::pair<bool, std::pair<size_type, size_type>> support(const size_type x) const
    {
        auto it = rs.upper_bound(x);
        it--;
        return {it->first <= x and it->second > x, *it};
    }
    const std::map<size_type, size_type>& data() const { return rs; }
    friend std::ostream& operator<<(std::ostream& os, const ranges& r)
    {
        os << "[ ";
        for (auto it = std::next(r.rs.begin()); it != std::prev(r.rs.end()); it++) { os << "[" << it->first << "," << it->second << "),"; }
        return os << " ]\n";
    }

private:
    std::map<size_type, size_type> rs;
};
int main()
{
    const auto N = read<ll>();
    auto X       = read<ll>();
    auto D       = read<ll>();
    if (D == 0) {
        std::cout << (X == 0 ? 1 : N + 1) << std::endl;
        return 0;
    }
    if (D < 0) { X = X + D * (N - 1), D = -D; }
    using pll = std::pair<ll, ll>;
    std::map<ll, pll> rs;
    ll ans = 0;
    for (ll n = 0; n <= N; n++) {
        SHOW(ans);
        SHOW(rs);
        const ll S = X * n;
        const ll M = ((S % D) + D) % D;
        const ll L = (S - M) / D + n * (n - 1) / 2;
        const ll R = (S - M) / D + n * (2 * N - n - 1) / 2 + 1;
        auto p     = rs[M];
        if (p.second <= L) {
            ans += (p.second - p.first);
            rs[M] = {L, R};
        } else if (p.first >= R) {
            ans += (p.second - p.first);
            rs[M] = {L, R};
        } else {
            chmin(p.first, L);
            chmax(p.second, R);
            rs[M] = p;
        }
    }
    SHOW(ans);
    SHOW(rs);
    for (const auto& pv : rs) {
        const auto& v = pv.second;
        ans += (v.second - v.first);
    }
    std::cout << ans << std::endl;
    return 0;
}


Measured memory_bytes: 12800