//#define NDEBUG
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <iostream>
#include <utility>
#include <vector>

namespace n91 {

using i8 = std::int_fast8_t;
using i32 = std::int_fast32_t;
using i64 = std::int_fast64_t;
using u8 = std::uint_fast8_t;
using u32 = std::uint_fast32_t;
using u64 = std::uint_fast64_t;
using isize = std::ptrdiff_t;
using usize = std::size_t;

struct rep {
  struct itr {
    usize i;
    constexpr itr(const usize i) noexcept : i(i) {}
    void operator++() noexcept { ++i; }
    constexpr usize operator*() const noexcept { return i; }
    constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
  };
  const itr f, l;
  constexpr rep(const usize f, const usize l) noexcept
      : f(std::min(f, l)), l(l) {}
  constexpr auto begin() const noexcept { return f; }
  constexpr auto end() const noexcept { return l; }
};
struct revrep {
  struct itr {
    usize i;
    constexpr itr(const usize i) noexcept : i(i) {}
    void operator++() noexcept { --i; }
    constexpr usize operator*() const noexcept { return i; }
    constexpr bool operator!=(const itr x) const noexcept { return i != x.i; }
  };
  const itr f, l;
  constexpr revrep(const usize f, const usize l) noexcept
      : f(l - 1), l(std::min(f, l) - 1) {}
  constexpr auto begin() const noexcept { return f; }
  constexpr auto end() const noexcept { return l; }
};
template <class T> auto md_vec(const usize n, const T &value) {
  return std::vector<T>(n, value);
}
template <class... Args> auto md_vec(const usize n, Args... args) {
  return std::vector<decltype(md_vec(args...))>(n, md_vec(args...));
}
template <class T> constexpr T difference(const T &a, const T &b) noexcept {
  if (a < b) {
    return b - a;
  } else {
    return a - b;
  }
}
template <class T> void chmin(T &a, const T &b) noexcept {
  if (b < a) {
    a = b;
  }
}
template <class T> void chmax(T &a, const T &b) noexcept {
  if (a < b) {
    a = b;
  }
}
template <class F> class fix_point : private F {
public:
  explicit constexpr fix_point(F &&f) : F(std::forward<F>(f)) {}

  template <class... Args>
  constexpr decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, std::forward<Args>(args)...);
  }
};
template <class F> constexpr decltype(auto) make_fix(F &&f) {
  return fix_point<F>(std::forward<F>(f));
}
template <class T> T scan() {
  T ret;
  std::cin >> ret;
  return ret;
}

} // namespace n91
#include <cassert>
#include <cstddef>
#include <functional>
#include <vector>

namespace n91 {

template <class T, class Operate = std::plus<T>, class Invert = std::negate<T>>
class cumulative_sum {
public:
  using value_type = T;

private:
  using size_t = std::size_t;

  Operate oper;
  Invert inve;
  std::vector<T> prefix;

public:
  cumulative_sum() = default;
  explicit cumulative_sum(const std::vector<T> &c,
                          const Operate &oper = Operate(), const T &iden = T(),
                          const Invert &inve = Invert())
      : oper(oper), inve(inve), prefix() {
    prefix.reserve(c.size() + 1);
    prefix.push_back(iden);
    for (const T &e : c) {
      prefix.push_back(oper(prefix.back(), e));
    }
  }

  T fold(const size_t first, const size_t last) const {
    assert(first <= last);
    assert(last < prefix.size());
    return oper(inve(prefix[first]), prefix[last]);
  }
  T operator[](const size_t index) const { return fold(index, index + 1); }
};

} // namespace n91

#include <algorithm>
#include <iostream>
#include <map>
#include <utility>
#include <vector>

namespace n91 {

void main_() {
  /*
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);
  //*/
  const usize n = scan<usize>();
  i64 x = scan<i64>();
  i64 d = scan<i64>();
  if (d == 0) {
    if (x == 0) {
      std::cout << 1 << std::endl;
    } else {
      std::cout << n + 1 << std::endl;
    }
    return;
  }
  if (d < 0) {
    x = x + d * (n - 1);
    d = -d;
  }
  struct range_t {
    i64 left;
    i64 right;
  };
  std::map<i64, std::vector<range_t>> mp;
  const i64 n_ = n;
  const auto divfl = [&](const i64 t) {
    if (t >= 0) {
      return t / d;
    } else {
      return (t - d + 1) / d;
    }
  };
  for (i64 i = 0; i <= n; i += 1) {
    const i64 rem = ((x % d) * (i % d) % d + d) % d;
    const i64 left = divfl(x * i) + i * (i - 1) / 2;
    const i64 right = divfl(x * i) + i * (n_ * 2 - i - 1) / 2;
    mp[rem].push_back({left, right + 1});
  }
  i64 ans = 0;
  for (auto &v_ : mp) {
    auto &v = v_.second;
    std::sort(v.begin(), v.end(), [](const auto &l, const auto &r) {
      if (l.left != r.left) {
        return l.left < r.left;
      } else {
        return l.right > r.right;
      }
    });
    i64 max = std::numeric_limits<i64>::lowest();
    std::vector<range_t> temp;
    for (const auto &e : v) {
      if (e.right > max) {
        temp.push_back(e);
      }
      chmax(max, e.right);
    }
    for (const usize i : rep(0, temp.size() - 1)) {
      ans += std::min(temp[i].right, temp[i + 1].left) - temp[i].left;
    }
    ans += temp.back().right - temp.back().left;
  }
  std::cout << ans << std::endl;
}

} // namespace n91

int main() {
  n91::main_();
  return 0;
}


Measured memory_bytes: 22144