#include <bits/stdc++.h>
using namespace std;
 
typedef long long db;
typedef long long ll;
const db eps=0;
const db INF=1e10;
int sign(db k){
	if (k>eps) return 1;
	else if (k<-eps) return -1;
	return 0;
}
int cmp(db k1,db k2){return sign(k1-k2);}
int inmid(db k1,db k2,db k3){return sign(k1-k3)*sign(k2-k3)<=0;}
 
struct point{
	db x,y;
	point operator + (const point &k1) const{return (point){x+k1.x,y+k1.y};}
	point operator - (const point &k1) const{return (point){x-k1.x,y-k1.y};}
	point operator * (db k1) const{return (point){x*k1,y*k1};}
	db abs2(){
		return x*x+y*y;	
	}
	db dis2(point k1){
		return ((*this)-k1).abs2();
	}
	bool operator < (const point &k1) const{
		int fl=cmp(x,k1.x);
		if (fl==-1) return true;
		if (fl==1) return false;
		return cmp(y,k1.y)==-1;	
	}
	bool operator == (const point &k1) const{
		return cmp(x,k1.x)==0 && cmp(y,k1.y)==0;	
	}
	bool operator > (const point &k1) const{
		int fl=cmp(x,k1.x);
		if (fl==1) return true;
		if (fl==-1) return false;
		return cmp(y,k1.y)==1;	
	}
	int getP(){
		return sign(y)==-1 || (sign(y)==0 && sign(x)==-1);
	}
	friend ostream& operator << (ostream &os,const point &k){
        os << "(" << k.x << "," << k.y << ")";
        return os;
    }
};
 
int inmid(point k1,point k2,point k3){
	return inmid(k1.x,k2.x,k3.x) && inmid(k1.y,k2.y,k3.y);	
}
db cross(point k1,point k2){
	return k1.x*k2.y-k1.y*k2.x;
}
db dot(point k1,point k2){
	return k1.x*k2.x+k1.y*k2.y;	
}

vector<point> ConvexHull(vector<point> A,int flag=1){
	int n=A.size();
	vector<point>ans(n*2);
	sort(A.begin(),A.end());
	int now=-1;
	for (int i=0;i<(int)A.size();i++){
		while (now>0 && sign(cross(ans[now]-ans[now-1],A[i]-ans[now-1]))<flag) now--;
		ans[++now]=A[i];
	}
	int pre=now;
	for (int i=n-2;i>=0;i--){
		while (now>pre && sign(cross(ans[now]-ans[now-1],A[i]-ans[now-1]))<flag) now--;
		ans[++now]=A[i];
	}
	ans.resize(now);
	return ans;
}
 
struct Convex{
	int n;
	vector<point> a,upper,lower;
	Convex(vector<point> _a):a(_a){
		n=a.size();
		int ptr=0;
		for (int i=1;i<n;i++) if (a[ptr]<a[i]) ptr=i;
		for (int i=0;i<=ptr;i++) lower.push_back(a[i]);
		for (int i=ptr;i<n;i++) upper.push_back(a[i]);
		upper.push_back(a[0]);
	}
	int sign(long long x){
		return x<0?-1:x>0;	
	}
	void update_tangent(const point &p,int id,int &i0,int &i1){
		if (cross(a[i0]-p,a[id]-p)>0) i0=id;
		if (cross(a[i1]-p,a[id]-p)<0) i1=id;	
	}
	void binary_search(int l,int r,point p,int &i0,int &i1){
		if (l==r) return;
		update_tangent(p,l%n,i0,i1);
		int sl=sign(cross(a[l%n]-p,a[(l+1)%n]-p));
		for (;l+1<r;){
			int mid=(l+r)/2;
			int smid=sign(cross(a[mid%n]-p,a[(mid+1)%n]-p));
			if (smid==sl) l=mid;
			else r=mid;
		}
		update_tangent(p,r%n,i0,i1);
	}
	bool contain(point p){
		if (p.x<lower[0].x || p.x>lower.back().x) return false;
		int id=lower_bound(lower.begin(),lower.end(),(point){p.x,-INF})-lower.begin();
		if (lower[id].x==p.x){
			if (lower[id].y>p.y) return false;	
		}
		else if (cross(lower[id-1]-p,lower[id]-p)<0)
			return false;
		id=lower_bound(upper.begin(),upper.end(),(point){p.x,INF},greater<point>())-upper.begin();
		if (upper[id].x==p.x){
			if (upper[id].y<p.y) return false;	
		}
		else if (cross(upper[id-1]-p,upper[id]-p)<0) return false;
		return true;
	}
	bool get_tangent(point p,int &i0,int &i1){
		if (contain(p)) return false;
		i0=i1=0;
		int id=lower_bound(lower.begin(),lower.end(),p)-lower.begin();
		binary_search(0,id,p,i0,i1);
		binary_search(id,(int)lower.size(),p,i0,i1);
		id=lower_bound(upper.begin(),upper.end(),p,greater<point>())-upper.begin();
		binary_search((int)lower.size()-1,(int)lower.size()-1+id,p,i0,i1);
		binary_search((int)lower.size()-1+id,(int)lower.size()-1+(int)upper.size(),p,i0,i1);
		return true;
	}
};

int main(){
	int n;
	cin >> n;
	vector<point> wp;
	vector<point> bp;
	db cntw=0,cntb=0;
	for (int i=1;i<=n;i++){
		db x,y;
		int col;
		cin >> x >> y >> col;
		if (col==0){
			cntw++;
			wp.emplace_back((point){x,y});	
		}
		else{
			cntb++;
			bp.emplace_back((point){x,y});
		}
	}
	
	if (cntb==1){
		cout << 1 << "\n";
		return 0;
	}
	
	db ans=cntb;
	sort(bp.begin(),bp.end());
	bp.resize(unique(bp.begin(),bp.end())-bp.begin());
	
	vector<point> CHB=bp;
	if (bp.size()>=3) CHB=ConvexHull(bp);
	if (CHB.size()<=2){
		point st=CHB.front();
		point ed=CHB.back();
		for (auto P:wp) if (inmid(st,ed,P)) ans++;
		cout << ans << "\n";
		return 0;	
	}
	
//	cerr << "---------------------" << endl;
//	cerr << "Convex Hull of black : " << endl;
//	for (auto e:CHB) cerr << e << endl;
//	cerr << "---------------------" << endl;
	
	ll base=0;
	Convex conv(CHB);
	vector<point> dir;
	vector<pair<point,ll>> vup;
	for (auto P:wp){
		int st=0,ed=0;
		bool flag=conv.get_tangent(P,st,ed);
		if (!flag){
			ans++;
			continue;
		}
		point dirst=CHB[st]-P;
		point dired=CHB[ed]-P;
		if (sign(cross(dirst,dired))<0) swap(dirst,dired);
		
		if (dirst.getP()) dirst=dirst*(-1);
		if (dired.getP()) dired=dired*(-1);
		dir.emplace_back(dirst);
		dir.emplace_back(dired);
		vup.emplace_back(dirst,1LL);
		vup.emplace_back(dired,-1LL);
		if (sign(cross(dirst,dired))<0) base++;
	}
	dir.emplace_back((point){1,0});
	sort(dir.begin(),dir.end(),
		[&](const point &X,const point &Y){
            return sign(cross(X,Y))>0;
        }
	);
	dir.resize(
		unique(dir.begin(),dir.end(),
			[&](const point &X,const point &Y){
        		return sign(cross(X,Y))==0;
        	}
		)
		-dir.begin()
	);
	dir.emplace_back((point){-1,0});
	{
		vector<point> tmp;
		int sz=dir.size();
		for (int i=0;i<=sz-2;i++){
			tmp.emplace_back(dir[i]);
			tmp.emplace_back(dir[i]+dir[i+1]);	
		}
		swap(dir,tmp);
	}
	
//	cerr << "ans : " << ans << endl;
//	for (auto d:dir){
//		cerr << "dir : " << d << endl;	
//	}
	
	auto cmp = [&](const pair<point,ll> &X,const pair<point,ll> &Y){
        int flag=sign(cross(X.first,Y.first));
        if (flag!=0) return flag==1;
        return X.second>Y.second;
    };
	sort(vup.begin(),vup.end(),cmp);
	vector<ll> sumup(vup.size()+1);
    if (vup.size()) sumup[0]=vup[0].second;
	for (int i=1;i<(int)vup.size();i++) sumup[i]=sumup[i-1]+vup[i].second;
	
//	for (auto [vec,val]:dir){
//		cerr << "vec,val : " << vec << " " << val << endl;	
//	}
	
	ll mn=1e9;
	for (auto d:dir){
		int pos=upper_bound(vup.begin(),vup.end(),make_pair(d,0LL),cmp)-vup.begin()-1;
		mn=min(mn,base+sumup[pos]);
	}
	ans+=mn;
	cout << ans << "\n";
	return 0;	
}