#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
using std::cout;
using std::cin;
using std::endl;
using ll=long long;
using ld=long double;
ll ILL=2167167167167167167;
const int INF=2100000000;
const ll mod=998244353;
#define rep(i,a,b) for (ll i=a;i<b;i++)
#define all(p) p.begin(),p.end()
template<class T> using _pq = priority_queue<T, vector<T>, greater<T>>;
template<class T> ll LB(vector<T> &v,T a){return lower_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> ll UB(vector<T> &v,T a){return upper_bound(v.begin(),v.end(),a)-v.begin();}
template<class T> bool chmin(T &a,const T &b){if(a>b){a=b;return 1;}else return 0;}
template<class T> bool chmax(T &a,const T &b){if(a<b){a=b;return 1;}else return 0;}
template<class T> void So(vector<T> &v) {sort(v.begin(),v.end());}
template<class T> void Sore(vector<T> &v) {sort(v.begin(),v.end(),[](T x,T y){return x>y;});}
void yneos(bool a){if(a) cout<<"Yes\n"; else cout<<"No\n";}
template<class T> void vec_out(vector<T> &p){for(int i=0;i<(int)(p.size());i++){if(i) cout<<" ";cout<<p[i];}cout<<"\n";}
template<class T> T min(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmin(ans,x);return ans;}
template<class T> T max(vector<T> &a){assert(!a.empty());T ans=a[0];for(auto &x:a) chmax(ans,x);return ans;}
template<class T> T sum(vector<T> &a){assert(!a.empty());T ans=a[0]-a[0];for(auto &x:a) ans+=x;return ans;}



void solve();
// oddloop
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	int t=1;
	//cin>>t;
	rep(i,0,t) solve();
}

void solve(){
	int N;
	cin>>N;
	int ans=N;
	vector<pair<int,int>> p(N);
	rep(i,0,N){
		cin>>p[i].first>>p[i].second;
	}
	So(p);
	if(N<=2){
		cout<<"1\n";
		return;
	}
	auto f=[&](pair<int,int> &a,pair<int,int> &b,pair<int,int> &c)->int{
		int A=b.second-a.second;
		int B=a.first-b.first;
		int C=a.second*b.first-b.second*a.first;
		return A*c.first+B*c.second+C;
	};
	do{
		vector<int> dp(N-1,N);
		dp[0]=1;
		rep(i,0,N-2){
			chmin(dp[i+1],1+dp[i]);
			int A=p[i+1].first-p[i].first;
			int B=p[i+1].second-p[i].second;
			int C=p[i+2].first-p[i+1].first;
			int D=p[i+2].second-p[i+1].second;
			int tmp=__gcd(abs(A),abs(B));
			A/=tmp,B/=tmp;
			tmp=__gcd(abs(C),abs(D));
			C/=tmp,D/=tmp;
			if(A==C&&D==B){
				chmin(dp[i+1],dp[i]);
				continue;
			}
			if(i==N-3) continue;
			int X=f(p[i+1],p[i+2],p[i+3]);
			int Y=f(p[i+1],p[i+2],p[i]);
			if(X==0) continue;
			if((X<0)^(Y<0)) continue;
			X=f(p[i],p[i+1],p[i+2]);
			Y=f(p[i],p[i+1],p[i+3]);
			if(X<0) X*=-1,Y*=-1;
			if(X<Y) chmin(dp[i+2],dp[i]+1);
		}
		if(chmin(ans,dp[N-2])){
			//vec_out(dp);
			//rep(i,0,N) cout<<p[i].first<<" "<<p[i].second<<"\n";
		}
	}while(next_permutation(all(p)));
	cout<<ans<<"\n";
}