#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
using P = pair<int, int>;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

bool f[1005];

ll func(ll x1, ll y1, ll x2, ll y2){
    return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;
    vector<ll> x(n), y(n);
    for(int i = 0; i < n; ++i)  cin >> x[i] >> y[i];

    using tup = tuple<ll, int, int>;
    priority_queue<tup, vector<tup>, greater<tup>> que;
    for(int i = 0; i < n; ++i){
        for(int j = 0; j < i; ++j){
            que.emplace(func(x[i], y[i], x[j], y[j]), j, i);
        }
    }

    int ans = 0;
    while(!que.empty()){
        auto [d, i, j] = que.top();
        que.pop();
        if(f[i] || f[j])    continue;
        f[j] = true;
        if(i == 0)  ans += 1;
        else    f[i] = true;
    }

    cout << ans << endl;

    return 0;
}