// need
#include <iostream>
#include <algorithm>
// data structure
#include <bitset>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <utility>
#include <vector>
#include <complex>
//#include <deque>
#include <valarray>
#include <unordered_map>
#include <unordered_set>
#include <array>
// etc
#include <cassert>
#include <cmath>
#include <functional>
#include <iomanip>
#include <chrono>
#include <random>
#include <numeric>

// input
#define INIT std::ios::sync_with_stdio(false);std::cin.tie(0);
#define VAR(type, ...)type __VA_ARGS__;MACRO_VAR_Scan(__VA_ARGS__);
template<typename T> void MACRO_VAR_Scan(T& t) { std::cin >> t; }
template<typename First, typename...Rest>void MACRO_VAR_Scan(First& first, Rest& ...rest) { std::cin >> first; MACRO_VAR_Scan(rest...); }
#define VEC_ROW(type, n, ...)std::vector<type> __VA_ARGS__;MACRO_VEC_ROW_Init(n, __VA_ARGS__); for(int w_=0; w_<n; ++w_){MACRO_VEC_ROW_Scan(w_, __VA_ARGS__);}
template<typename T> void MACRO_VEC_ROW_Init(int n, T& t) { t.resize(n); }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Init(int n, First& first, Rest& ...rest) { first.resize(n); MACRO_VEC_ROW_Init(n, rest...); }
template<typename T> void MACRO_VEC_ROW_Scan(int p, T& t) { std::cin >> t[p]; }
template<typename First, typename...Rest>void MACRO_VEC_ROW_Scan(int p, First& first, Rest& ...rest) { std::cin >> first[p]; MACRO_VEC_ROW_Scan(p, rest...); }
#define VEC(type, c, n) std::vector<type> c(n);for(auto& i:c)std::cin>>i;
#define MAT(type, c, m, n) std::vector<std::vector<type>> c(m, std::vector<type>(n));for(auto& R:c)for(auto& w:R)std::cin>>w;
// output
#define OUT(dist) std::cout<<(dist);
#define FOUT(n, dist) std::cout<<std::fixed<<std::setprecision(n)<<(dist);
#define SOUT(n, c, dist) std::cout<<std::setw(n)<<std::setfill(c)<<(dist);
#define SERR(n, c, dist) std::cerr<<std::setw(n)<<std::setfill(c)<<(dist);
#define SP std::cout<<" ";
#define TAB std::cout<<"\t";
#define BR std::cout<<"\n";
#define SPBR(w, n) std::cout<<(w + 1 == n ? '\n' : ' ');
#define ENDL std::cout<<std::endl;
#define FLUSH std::cout<<std::flush;
#define SHOW(dist) {std::cerr << #dist << "\t: " << (dist) << "\n";}
#define SHOWVECTOR(v) {std::cerr << #v << "\t: ";for(const auto& xxx : v){std::cerr << xxx << " ";}std::cerr << "\n";}
#define SHOWVECTOR2(v) {std::cerr << #v << "\t:\n";for(const auto& xxx : v){for(const auto& yyy : xxx){std::cerr << yyy << " ";}std::cerr << "\n";}}
#define SHOWQUEUE(a) {auto tmp(a);std::cerr << #a << "\t:";while(!tmp.empty()){std::cerr << tmp.front() << " ";tmp.pop();}std::cerr << "\n";}
#define SHOWSTACK(a) {auto tmp(a);std::cerr << #a << "\t:";while(!tmp.empty()){std::cerr << tmp.top() << " ";tmp.pop();}std::cerr << "\n";}
// utility
#define ALL(a) (a).begin(),(a).end()
#define FOR(w, a, n) for(int w=(a);w<(n);++w)
#define RFOR(w, a, n) for(int w=(n)-1;w>=(a);--w)
#define REP(w, n) for(int w=0;w<int(n);++w)
#define RREP(w, n) for(int w=int(n)-1;w>=0;--w)
#define IN(a, x, b) (a<=x && x<b)
template<class T> inline T CHMAX(T& a, const T b) { return a = (a < b) ? b : a; }
template<class T> inline T CHMIN(T& a, const T b) { return a = (a > b) ? b : a; }
// test
template<class T> using V = std::vector<T>;
template<class T> using VV = V<V<T>>;

template<typename S, typename T>
std::ostream& operator<<(std::ostream& os, std::pair<S, T> p) {
	os << "(" << p.first << ", " << p.second << ")"; return os;
}

// type/const
#define int ll
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using PAIR = std::pair<int, int>;
using PAIRLL = std::pair<ll, ll>;
constexpr int INFINT = (1 << 30) - 1;                    // 1.07x10^ 9
constexpr int INFINT_LIM = (1LL << 31) - 1;              // 2.15x10^ 9
constexpr ll INFLL = 1LL << 60;                          // 1.15x10^18
constexpr ll INFLL_LIM = (1LL << 62) - 1 + (1LL << 62);  // 9.22x10^18
constexpr double EPS = 1e-6;
constexpr int MOD = 1000000007;
constexpr double PI = 3.141592653589793238462643383279;
template<class T, size_t N> void FILL(T(&a)[N], const T& val) { for (auto& x : a) x = val; }
template<class ARY, size_t N, size_t M, class T> void FILL(ARY(&a)[N][M], const T& val) { for (auto& b : a) FILL(b, val); }
template<class T> void FILL(std::vector<T>& a, const T& val) { for (auto& x : a) x = val; }
template<class ARY, class T> void FILL(std::vector<std::vector<ARY>>& a, const T& val) { for (auto& b : a) FILL(b, val); }
// ------------>8------------------------------------->8------------

// Description: 区間をsetで管理するデータ構造(なお実装はmap)．各クエリO(log区間数)．

// #### attention! : [l, r] ( include r, not [l, r) )
class SegmentMap : public std::map<ll, ll> {
private:
	bool flagToMergeAdjacentSegment;
public:
	// if merge [l, c] and [c+1, r], set flagToMergeAdjacentSegment to true
	SegmentMap() :
		flagToMergeAdjacentSegment(true) {}
	// __exist -> iterator pair(l, r) (contain p)
	// noexist -> map.end()
	auto get(ll p) const {
		auto it = upper_bound(p);
		if (it == begin() || (--it)->second < p) return end();
		return it;
	}
	// insert segment [l, r]
	void insert(ll l, ll r) {
		auto itl = upper_bound(l), itr = upper_bound(r + flagToMergeAdjacentSegment);
		if (itl != begin()) {
			if ((--itl)->second < l - flagToMergeAdjacentSegment) ++itl;
		}
		if (itl != itr) {
			l = std::min(l, itl->first);
			r = std::max(r, std::prev(itr)->second);
			erase(itl, itr);
		}
		(*this)[l] = r;
	}
	// remove segment [l, r]
	void remove(ll l, ll r) {
		auto itl = upper_bound(l), itr = upper_bound(r);
		if (itl != begin()) {
			if ((--itl)->second < l) ++itl;
		}
		if (itl == itr) return;
		int tl = std::min(l, itl->first), tr = std::max(r, std::prev(itr)->second);
		erase(itl, itr);
		if (tl < l) (*this)[tl] = l - 1;
		if (r < tr) (*this)[r + 1] = tr;
	}
	// Is p and q in same segment?
	bool same(ll p, ll q) const {
		const auto&& it = get(p);
		return it != end() && it->first <= q && q <= it->second;
	}
};

int mydiv(int a, int b) {
	if (a >= 0) return a / b;
	return a / b + (a % b == 0) - 1;
}

signed main() {
	INIT;

	VAR(int, n, x, d);

	if (d == 0) {
		if (x == 0) {
			OUT(1)BR;
		}
		else {
			OUT(n + 1)BR;
		}
		return 0;
	}
	if (d < 0) {
		x = x + (n - 1) * d;
		d = -d;
	}

	V<int> c(n + 1, 0);
	REP(i, n) {
		c[i + 1] = c[i] + (x + i * d);
	}

	std::map<int, SegmentMap> map;
	REP(k, n + 1) {
		int X = c[k], Y = c[n] - c[n - k];
		int mi = X - (c[n] - X), ma = Y - (c[n] - Y);
		int r = (mi % (2 * d) + 2 * d) % (2 * d);
		int r2 = (ma % (2 * d) + 2 * d) % (2 * d);
		map[r].insert(mydiv(mi, (2 * d)), mydiv(ma, (2 * d)));
	}
	int ans = 0;
	for (auto& p : map) {
		auto it = p.second.begin();
		while (it != p.second.end()) {
			ans += it->second - it->first + 1;
			++it;
		}
	}
	OUT(ans)BR;

	return 0;
}

Measured memory_bytes: 36224