#include <bits/stdc++.h>
#include <unistd.h>
 
using namespace std;
 
typedef long long ll;
typedef pair<ll,ll> P;
 
long long int INF = 1e18;
const ll fact_table = 5000000;
double Pi = 3.1415926535897932384626;
 
vector<ll> G[550010];
vector<pair<ll, double> > tree[500010];
priority_queue <ll> pql;
priority_queue <P> pqp;
//big priority queue
priority_queue <ll,vector<ll>,greater<ll> > pqls;
priority_queue <P,vector<P>,greater<P> > pqps;
//small priority queue
//top pop
 
int dx[8]={1,0,-1,0,1,1,-1,-1};
int dy[8]={0,1,0,-1,1,-1,-1,1};
char dir[] = "DRUL";
//ll bit[500005];
//↓,→,↑,←
 
 
#define p(x) cout<<x<<"\n";
#define el cout<<"\n";
#define pe(x) cout<<(x)<<" ";
#define ps(x) cout<<fixed<<setprecision(25)<<x<<endl;
#define pu(x) cout<<(x);
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define CLEAR(a) a = decltype(a)(); 
 
 
//ll mod = 998244353;
ll mod = 1000000007;
 
ll rui(ll number1,ll number2){
 
    if(number2 == 0){
        return 1;
    }else{
        ll number3 = rui(number1,number2 / 2);
        number3 *= number3;
        number3 %= mod;
        if(number2%2==1){
            number3 *= number1;
            number3 %= mod;
        }
        return number3;
    }
}
ll gcd(ll number1,ll number2){
 
    if(number1 > number2){
        swap(number1,number2);
    }
    if(number1 == 0 || number1 == number2){
        return number2;
    }else{
        return gcd(number2 % number1,number1);
    }
}
void YES(bool condition){
 
    if(condition){
        p("YES");
    }else{
        p("NO");
    }
    return;
}
void Yes(bool condition){
 
    if(condition){
        p("Yes");
    }else{
        p("No");
    }
    return;
}
 
/*
ll fact[fact_table + 5],rfact[fact_table + 5];
 
void c3_init(){
    fact[0] = rfact[0] = 1;
    for(ll i=1; i<=fact_table; i++){
        fact[i] = (fact[i-1]*i) % mod;
    }
    rfact[fact_table] = rui(fact[fact_table],mod - 2);
    for(ll i=fact_table; i>=1; i--){
       rfact[i-1] = rfact[i] * i;
       rfact[i-1] %= mod;
    }
    return;}
ll c3(ll n,ll r){
    return (((fact[n] * rfact[r]) % mod ) * rfact[n-r]) % mod;}
*/
 
ll n,m,num,sum,a,b,c,d,e,g,h,w,i,j,q,r,l;
ll k,ans;
ll x[500005],y[500005],z[500005];
char s[500005];

tuple<ll, ll, ll> table[700004];

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    cin >> n >> k >> d;
    if(d < 0){
        k = k + (n - 1) * d;
        d *= -1;
    }
    if(d == 0 && k == 0){
        p(1);
        return 0;
    }
    if(d == 0){
        p(n + 1);
        return 0;
    }
    for(ll i=0;i<=n;i++){
        ll sum_1 = i * k;
        ll left = (i - 1) * i / 2;
        ll right = ((n - 1) * n - (n - i - 1) * (n - i)) / 2;
        ll reside = sum_1 % d;
        reside = (reside + d) % d;
        ll move = (sum_1 - reside) / d;
        get<0>(table[i]) = reside;
        get<1>(table[i]) = left + move;
        get<2>(table[i]) = right + move;
    }
    sort(table, table + n + 1);
    get<0>(table[n+1]) = d + 100;
    get<1>(table[n+1]) = -1;
    get<2>(table[n+1]) = -1;
    ll now_reside = -INF;
    ll all_left = 1, all_right = 0;
    ll sum = 0;
    for(int i=0;i<=n+1;i++){
        ll reside = get<0>(table[i]);
        ll left = get<1>(table[i]);
        ll right = get<2>(table[i]);
        //pe(reside);pe(left);p(right);
        sum += right - left + 1;
    }
    for(int i=0;i<=n+1;i++){
        ll reside = get<0>(table[i]);
        ll left = get<1>(table[i]);
        ll right = get<2>(table[i]);
        if(now_reside != reside){
            now_reside = reside;
            ans += (all_right - all_left + 1);
            all_left = left;
            all_right = right;
        }else{
            if(left <= all_right){
                all_right = max(right, all_right);
            }else{
                ans += (all_right - all_left + 1);
                all_left = left;
                all_right = right;
            }
        }
    }
    assert(ans >= 0);
    p(ans);


    return 0;
}
 

Measured memory_bytes: 33024