#include<bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef vector<bool> vb;
typedef vector<vector<bool>> vvb;
typedef vector<vector<vector<bool>>> vvvb;
typedef pair<ll, ll> pll;
typedef vector<pll> vpll;
typedef vector<vpll> vvpll;
typedef vector<double> vd;
typedef vector<vd> vdd;

#define FOR(i,x,y) for(ll i=(ll)x; i<(ll)y; ++i)
#define REP(i,y) FOR(i, 0, y)
#define RFOR(i,x,y) for(ll i=(ll)x; i>=(ll)y; --i)
#define RREP(i,x) RFOR(i, x, 0)
#define ALL(a) a.begin(), a.end()
#define pb push_back
#define debug_print(x...) cerr << "line " << __LINE__ << " : "; debug_print_in(x);

template <typename First>
void debug_print_in(First first){
  cerr << first << endl;
  return;
}

template <typename First, typename... Rest>
void debug_print_in(First first, Rest... rest){
  cerr << first << " ";
  debug_print_in(rest...);
  return;
}

void IN(void){
  return;
}

template <typename First, typename... Rest>
void IN(First& first, Rest&... rest){
  cin >> first;
  IN(rest...);
  return;
}

template <typename First>
void OUT(First first){
  cout << first << endl;
  return;
}

template <typename First, typename... Rest>
void OUT(First first, Rest... rest){
  cout << first << " ";
  OUT(rest...);
  return;
}

template<class t, class u> void chmax(t&a,u b){if(a<b)a=b;};
template<class t, class u> void chmin(t&a,u b){if(a>b)a=b;};
int popcount(int t){return __builtin_popcount(t);} //GCC
int popcount(ll t){return __builtin_popcountll(t);} //GCC

template <typename T>
void vec_print(vector<T> VEC){
  REP(i, VEC.size()){
    cerr << VEC[i] << " ";
  }
  cerr << endl;
};

template <typename T>
void mat_print(vector<vector<T> > MAT){
  REP(i,MAT.size()){
    REP(j,MAT[i].size()){
      cerr << MAT[i][j] << " ";
    }
    cerr << endl;
  }
};

constexpr int INF = (1<<30);
constexpr ll INFLL = 1LL<<62;
constexpr long double EPS = 1e-12;
constexpr ll MOD = (ll)((1E+9)+7);

ll lcm(ll x, ll y){
  if(y==0) return x;
  return lcm(y, x%y);
}

int main(){
  cin.tie(0); // cut the cin and cout (default, std::flush is performed after std::cin)
  ios::sync_with_stdio(false); // cut the iostream and stdio (DON'T endl; BUT "\n";)

  ll N, X, D;
  IN(N,X,D);

  map<ll, vector<pair<ll, ll>>> mp;

  if(D==0){
    if(X==0) OUT(1);
    else     OUT(N+1);
    return 0;
  }

  if(D<0){
    X = -X;
    D = -D;
  }

  REP(k,N+1){
    ll base = k*X;
    ll index = base;
    if(index<0){
      index += D*((-index)/D);
      while(index<0) index += D;
    }
    index %= D;
    ll start = k*(k-1)*D/2 + base;
    ll end = k*(k-1)*D/2 + (N-k)*k*D + base;
    if(mp.find(index)==mp.end()){
      vpll tmp(1, make_pair(start, end));
      mp[index] = tmp;
    }else{
      mp[index].pb(make_pair(start, end));
    }
  }

  ll ans = 0;
  for(auto itr:mp){
    vpll tmp = itr.second;
    sort(ALL(tmp));
    ll begin = tmp[0].first;
    ll end = tmp[0].second;
    ans += (end-begin)/D+1;
    FOR(i,1,tmp.size()){
      ll begin_tmp = tmp[i].first;
      ll end_tmp = tmp[i].second;
      if(end<begin_tmp){
        ans += (end_tmp-begin_tmp)/D+1;
        end = end_tmp;
      }else if(end_tmp<=end){
        continue;
      }else{
        ans += (end_tmp-end)/D;
        end = end_tmp;
      }
    }
  }

  OUT(ans);

  return 0;
}

Measured memory_bytes: 22144