//////////////////////////////
// Check before you submit.
// #define _ATCODER_LIBRARY

const long long MOD = 1e9+7;
// const long long MOD = 998244353;

/////////////////////////////
#include <bits/stdc++.h>
using namespace std;
#include <boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;

#ifdef _ATCODER_LIBRARY
#include <atcoder/all>
using namespace atcoder;
#endif
// _ATCODER_LIBRARY

const long long INF = 1LL << 60;
using ll = long long;
using P = pair<ll, ll>;

#define FOR(i,a,b) for (ll i=(a);i<(ll)(b);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define SUM(v) accumulate(ALL(v),0ll)

template<typename T>istream& operator>>(istream&i,vector<T>&v){REP(j,v.size())i>>v[j];return i;}
template<typename T>string join(vector<T>&v){stringstream s;REP(i,v.size())s<<' '<<v[i];return s.str().substr(1);}
template<typename T>ostream& operator<<(ostream&o,vector<T>&v){if(v.size())o<<join(v);return o;}
template<typename T>string join(vector<vector<T>>&vv){string s="\n";REP(i,vv.size())s+=join(vv[i])+"\n";return s;}
template<typename T>ostream& operator<<(ostream&o,vector<vector<T>>&vv){if(vv.size())o<<join(vv);return o;}
template<typename T1,typename T2>istream& operator>>(istream&i,pair<T1,T2>&v){return i>>v.first>>v.second;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,pair<T1,T2>&v){return o<<v.first<<","<<v.second;}

#define DEBUG(x);

#ifdef _DEBUG
#define DEBUG(x) std::cerr << #x << " : " << (x) << std::endl;
#define GLIBCXX_DEBUG
#define GLIBCXX_DEBUG_PEDANTIC
#endif
// _DEBUG

int dx[4]{0, 1, 0, -1};
int dy[4]{1, 0, -1, 0};

void init_init_init() {ios_base::sync_with_stdio(false);cin.tie(NULL);std::cout<<fixed<<setprecision(10);}
template<class T>T up(T a, T b){assert(b);return (a+b-1)/b;}
template<typename... A>bool eq(A const&... a){auto t={a...};assert(t.size());auto tar=*t.begin();for(const auto&e:t)if(tar!=e)return false;return true;}

template<class T>bool chmin(T &a, T b){if(a>b){a=b;return false;}return true;}
template<class T>bool chmax(T &a, T b){if(a<b){a=b;return false;}return true;}
template<class T>bool chmax(T &a, initializer_list<T>l){return chmax(a,max(l));}
template<class T>bool chmin(T &a, initializer_list<T>l){return chmin(a,min(l));}

//////////////////////////////////////////////////////////////////
// My Library
//////////////////////////////////////////////////////////////////



//////////////////////////////////////////////////////////////////
// Contest Code
//////////////////////////////////////////////////////////////////



int main(int argc, char **argv)
{
	init_init_init();

	ll N; cin >> N;
	vector<ll> x(N), y(N); REP(i, N) cin >> x[i] >> y[i];

	ll res{0};

	auto f = [](ll x1, ll x2, ll y1, ll y2)
			 {
				 return sqrt(pow(x1-x2, 2) + pow(y1-y2, 2));
			 };

	set<ll> is;
	set<ll> del;
	while (true)
	{
		ll j{-1};
		double ma{INF};
		REP(i, N)
		{
			if (del.count(i)) continue;
			if (is.count(i)) continue;
			if (i == 0) continue;
			long double t = f(x[0], x[i], y[0], y[i]);
			if (ma >= t)
			{
				j = i;
				ma = t;
			}
			DEBUG(ma);
		}

		if (j == -1) break;

		double mmi{INF};
		REP(i, N)
		{
			if (del.count(i)) continue;
			if (i == 0) continue;
			if (i == j) continue;

			chmin(mmi, f(x[j], x[i], y[j], y[i]));
			DEBUG(mmi);
		}

		
		if (ma <= mmi)
			del.insert(j);
		is.insert(j);
	}

	std::cout << del.size() << std::endl; 
}