#include<cstdio>

#include<cmath>

#include<algorithm>

using namespace std;

const double eps=0.0000001;

struct Point{

    double x,y;

    Point(const double &x,const double &y){

        this->x=x;

        this->y=y;

    }

    Point(){}

    void read(){

        scanf("%lf%lf",&x,&y);

    }

    double length(){

        return sqrt(x*x+y*y);

    }

}a[100005];

typedef Point Vector;

Vector operator - (const Point &a,const Point &b){

    return Vector(a.x-b.x,a.y-b.y);

}

double Cross(const Vector &a,const Vector &b){

    return a.x*b.y-a.y*b.x;

}

double DisToLine(Point P,Point A,Point B)

{

	Vector v1=B-A,v2=P-A;

	return fabs(Cross(v1,v2))/v1.length();

}

int n,r,w,h;

pair<double,int> b[100005];

struct data{

    double v;

    int p;

    data(const double &v,const int &p){

        this->v=v;

        this->p=p;

    }

    data(){}

}t[100005];

bool cmp(const data &a,const data &b){

    return a.v<b.v;

}

bool cm2(const pair<double,int> &a,const pair<double,int> &b){

    return a.second<b.second;

}

int ans;

int maxv[100005<<2];

void update(int p,int v,int rt,int l,int r){

    if(l==r){

        maxv[rt]=v;

        return;

    }

    int m=(l+r>>1);

    if(p<=m){

        update(p,v,rt<<1,l,m);

    }

    else{

        update(p,v,rt<<1|1,m+1,r);

    }

    maxv[rt]=max(maxv[rt<<1],maxv[rt<<1|1]);

}

int query(int ql,int qr,int rt,int l,int r){

    if(ql<=l && r<=qr){

        return maxv[rt];

    }

    int m=(l+r>>1),res=0;

    if(ql<=m){

        res=max(res,query(ql,qr,rt<<1,l,m));

    }

    if(m<qr){

        res=max(res,query(ql,qr,rt<<1|1,m+1,r));

    }

    return res;

}

int main(){

    //freopen("g.in","r",stdin);

    scanf("%d%d%d%d",&n,&r,&w,&h);

    Point p=Point((double)w*0.5,-(double)w*(double)r*0.5);

    Point q=Point((double)w,0.0);

    Point yd=Point(0.0,0.0);

    for(int i=1;i<=n;++i){

        a[i].read();

        double d1=DisToLine(a[i],p,q);

        double d2=DisToLine(a[i],p,yd);

        a[i]=Point(d1,d2);

        b[i].first=d1;

        t[i].v=d2;

        t[i].p=i;

    }

    sort(t+1,t+n+1,cmp);

    int zy=0;

    b[t[1].p].second=++zy;

    for(int i=2;i<=n;++i){

        if(fabs(t[i].v-t[i-1].v)>eps){

            ++zy;

        }

        b[t[i].p].second=zy;

    }

    int sta;

    sort(b+1,b+n+1);

    for(int i=1;i<=n;++i){

        if(i==1 || fabs(b[i].first-b[i-1].first)>eps){

            sta=i;

        }

        if(i==n || fabs(b[i].first-b[i+1].first)>eps){

            sort(b+sta,b+i+1,cm2);

            for(int j=sta;j<=i;++j){

                int x=query(1,b[j].second,1,1,zy);

                ans=max(ans,x+1);

                update(b[j].second,x+1,1,1,zy);

            }

        }

    }

    printf("%d\n",ans);

    return 0;

}