#include<bits/stdc++.h>
#define up(a,b,c) for(int a=b;a<=c;++a)
const int N=2200;
using namespace std;
int n,m,k,ans;
struct ppt
{
	double x,y;
	void inp()
	{
		cin>>x>>y;
	}
	ppt operator - (ppt b)
	{
		return {x-b.x,y-b.y};
	}
	double sq()
	{
		return sqrt(x*x+y*y);
	}
	double operator * (ppt b)
	{
		return x*b.y-y*b.x;
	}
}e[N],p[N],ag[N];
bool cmp(ppt a,ppt b)
{
	double x=(a-e[1])*(b-e[1]);
	return x==0?(a-e[1]).sq()<(b-e[1]).sq():x>0; 
}
ppt qag(ppt A,ppt B,ppt C)
{
	double a=(B-C).sq(),b=(A-C).sq(),c=(A-B).sq();
	return {acos((b*b+c*c-a*a)/2/b/c),acos((a*a+c*c-b*b)/2/a/c)};
}
bool yhp(ppt a,ppt b)
{
	return a.x<b.x;
}
int main()
{
	cin>>n;
	up(i,1,n)
	{
		e[i].inp();
		if(e[i].x<e[1].x||(e[i].x==e[1].x&&e[i].y>e[1].y))swap(e[i],e[1]);
	}
	sort(e+2,e+n+1,cmp);
	m=1;
	up(i,2,n)
	{
		while(m>1&&(e[i]-e[m])*(e[m]-e[m-1])>=0)p[++k]=e[m],--m;
		swap(e[++m],e[i]);
	}
//	up(i,1,m)
//		cout<<e[i].x<<' '<<e[i].y<<'\n';
//	up(i,1,k)
//		cout<<p[i].x<<' '<<p[i].y<<'\n';
	up(i,1,m)
	{
		up(j,1,k)ag[j]=qag(e[i],e[i%m+1],p[j]);
		sort(ag+1,ag+k+1,yhp);
		double mx=5;
		up(j,1,k)
		{
		//	bool ok=1;
			if(mx>=ag[j].y)++ans;
			mx=min(mx,ag[j].y);
		/*	up(z,1,k)
				if(z!=j&&(ag[z].x<ag[j].x&&ag[z].y<ag[j].y))
					ok=0;
			ans+=ok;*/
		}
	}
	cout<<ans+1;
	return 0;
}