#include<bits/stdc++.h>
using namespace std;
#define ri register int
typedef long long ll;
const int maxn=1e5+10;
mt19937 rndNum(chrono::system_clock::now().time_since_epoch().count());
template<class T>
inline T genRnd(const T &limL,const T &limR){
	uniform_int_distribution<T>limLR(limL,limR);
	return limLR(rndNum);
}
inline ll sqr(ll k){return k*k;}
struct vec{
	ll x,y;
	inline vec(ll x_=0,ll y_=0):x(x_),y(y_){}
	inline vec operator-(const vec &k){
		return vec(x-k.x,y-k.y);
	}
	inline bool operator<(const vec &k)const{
		return x!=k.x?x<k.x:y<k.y;
	}
	inline ll cross(const vec &k){
		return x*k.y-y*k.x;
	}
	inline ll norm(){
		return x*x+y*y;
	}
	inline ll dist(const vec &k){
		return sqrt(sqr(x-k.x)+sqr(y-k.y));
	}
}a[maxn];
inline bool cmp(vec x,vec y){
	ll det=(x-a[0]).cross(y-a[0]);
	return det?det>0:(x-a[0]).norm()<(y-a[0]).norm();
}
int n,tp;
inline int graham(){
	vec tmp=a[1];
	for(ri i=1;i<n;++i)a[i]=a[i+1];
	a[n]=tmp;
	int ret=0;
	deque<vec>st;
	for(ri i=1;i<=n;++i){
		if(st.size()>1&&(a[i]-st.front()).cross(st.back()-st.front()))ret+=3,st.pop_front(),st.pop_back();
		else st.push_back(a[i]);
	}
	return ret;
}
int main(){
	while(~scanf("%d",&n)){
		a[0]={0,0};
		for(ri i=1;i<=n;++i){
			scanf("%lld%lld",&a[i].x,&a[i].y);
			a[0].x+=a[i].x,a[0].y+=a[i].y;
			a[i].x<<=1,a[i].y<<=1;
		}
		sort(a+1,a+n+1);
		printf("%d\n",n-max({graham(),graham(),graham()}));
	}
	return 0;
}