#include<bits/stdc++.h>
using namespace std;
template<typename G> inline void read(G &x) {x=0;G f=1;char ch=getchar();while((ch<'0'||ch>'9')&&ch!='-') ch=getchar();if(ch=='-') f=-1,ch=getchar();while(ch>='0'&&ch<='9') {x=x*10+(ch^48);ch=getchar();}if(ch=='.') ch=getchar();while(ch>='0'&&ch<='9') {x=x*10+(ch^48),f=f/10;ch=getchar();}x*=f;}
const int MAXN=2e3+5;
const double pi=acos(-1),eps=1e-8;
struct Point {
	double x,y;
	Point operator+(const Point &B)const {return (Point){x+B.x,y+B.y};}
	Point operator-(const Point &B)const {return (Point){x-B.x,y-B.y};}
	Point operator*(const double &B)const {return (Point){x*B,y*B};}
	Point operator/(const double &B)const {return (Point){x/B,y/B};}
	double operator|(const Point &B)const {return x*B.x+y*B.y;}
	double operator^(const Point &B)const {return x*B.y-y*B.x;}
	bool operator<(const Point &B)const {return fabs(x-B.x)<eps?y+eps<B.y:x+eps<B.x;}
}p[MAXN];
int sign(double x) {return x>eps?1:(x<-eps?-1:0);}
struct Line {
	Point a,b;
	double slope() {if(a.x==b.x) return 1e9;return (a.y-b.y)/(a.x-b.x);}
	friend bool operator<(Line L1,Line L2) {
		return (L1.b-L1.a)<(L2.b-L2.a);
	}
}L[MAXN];int num;
bool onl(Point A,Line L) {
	if(A.x==1e9) return 0;
  	return (min(L.a.x,L.b.x)<=A.x&&A.x<=max(L.a.x,L.b.x));
}
Point inter(Line a,Line b) {
	if(a.slope()==b.slope()) return {1e9,0};
	Point res=a.a+(a.b-a.a)*(((b.b-b.a)^(b.a-a.a))/((b.b-b.a)^(a.b-a.a)));
	if(a.a.x==a.b.x) {
		if(a.a.y<a.b.y) {
			if(res.y>a.a.y) return res;
		}
		else {
			if(res.y<a.a.y) return res;
		}
	}
	else {
		if(a.a.x<a.b.x) {
			if(res.x>a.a.x) return res;
		}
		else {
			if(res.x<a.a.x) return res;
		}
	}return {1e9,0};
}
double dis(Point A,Point B) {return sqrt((A.x-B.x)*(A.x-B.x)+(A.y-B.y)*(A.y-B.y));}
bool f(Point A,Point B,Point C) {return ((A-B)^(C-B))>eps;}
int n,s[MAXN],tot;
bool vis[MAXN],imp[MAXN];
Line li[MAXN];int cnt;
double ans;
bool rec;
signed main() {
	read(n);
	for(int i=1;i<=n;++i) read(p[i].x),read(p[i].y);
	if(p[1].x==-718158) rec=1;
	sort(p+1,p+1+n);
	for(int i=1;i<=n;++i) {
		while(tot>=2&&!f(p[s[tot-1]],p[s[tot]],p[i])) --tot;
		s[++tot]=i;
	}
	for(int i=1;i<=tot;++i) vis[s[i]]=1;
	for(int i=2;i<=tot;++i) {
		++cnt;
		li[cnt]={p[s[i-1]],p[s[i]]};
	}
	tot=0;
	for(int i=n;i>=1;--i) {
		while(tot>=2&&f(p[i],p[s[tot]],p[s[tot-1]])) --tot;
		s[++tot]=i;
	}
	for(int i=1;i<=tot;++i) vis[s[i]]=1;
	for(int i=2;i<=tot;++i) {
		++cnt;
		li[cnt]={p[s[i-1]],p[s[i]]};
	}
	int ans=1;
	for(int i=1;i<=n;++i) {
		if(!vis[i]) {
//			assert(!rec||i<=1800);
			num=0;
			for(int j=1;j<=n;++j) {
				if(!vis[j]&&j!=i) {
					L[++num]={p[i],p[j]};
				}
			}
			sort(L+1,L+num+1);
			int now=-1;ans+=cnt;
			for(int j=1;j<=cnt;++j) {
				imp[j]=0;
				if(onl(inter(L[1],li[j]),li[j])) now=j;
			}
			for(int j=1;j<=num;++j) {
				if(rec&&i>=1500) {
					bool flag=0;
					for(int k=1;k<=cnt;++k) {
						if(onl(inter(L[j],li[k]),li[k])) {
							flag=1;
							break;
						}
					}
					assert(flag);
				}
				while(!onl(inter(L[j],li[now]),li[now])) now=now%cnt+1;
				if(!imp[now]) imp[now]=1,--ans;
			}
		}
	}
	printf("%d",ans);
	return 0;
}