#include "bits/stdc++.h"
//#include <atcoder/all>

using namespace std;
//using namespace atcoder;

//#define int long long
#define ll long long
ll INF = (1LL << 60);
constexpr int mod = 1000000007;
using P = pair<int, int>;

void solve() {
	int N; cin >> N;
	vector<ll>x(N), y(N);
	for (int i = 0; i < N; i++) {
		cin >> x[i] >> y[i];
	}
	vector<pair<ll, P>>p;
	for (int i = 0; i < N; i++) {
		for (int j = i + 1; j < N; j++) {
			p.push_back({ (x[i] - x[j])*(x[i] - x[j]) + (y[i] - y[j])*(y[i] - y[j]), {i, j} });
		}
	}
	sort(p.begin(), p.end());
	vector<bool>seen(N);
	ll ans = 0;
	for (int i = 0; i < p.size(); i++) {
		if (!seen[p[i].second.first] && !seen[p[i].second.second]) {
			if (p[i].second.first == 0) {
				ans++;
				seen[p[i].second.second] = true;
			}
			else {
				seen[p[i].second.first] = true;
				seen[p[i].second.second] = true;
			}
		}
	}
	cout << ans << endl;
}
signed main() {
	int t; t = 1;
	for (int i = 0; i < t; i++) {
		solve();
	}
	return 0;
}