#include <bits/stdc++.h>
using namespace std;
using namespace chrono;

int main()
{
	int64_t n;
	cin >> n;
	vector<int64_t> xs(n), ys(n);
	for (int64_t i = 0; i < n; i++)
	{
		cin >> xs[i] >> ys[i];
	}

	auto dist = [&](int64_t i, int64_t j) {
		return (xs[i] - xs[j]) * (xs[i] - xs[j]) + (ys[i] - ys[j]) * (ys[i] - ys[j]);
	};

	int64_t inf = (1LL << 60);

	priority_queue<pair<int64_t, int64_t>, vector<pair<int64_t, int64_t>>, greater<>> pq;

	for (int64_t i = 1; i < n; i++)
	{
		pq.emplace(dist(0, i), i);
	}

	vector<bool> rm(n, false);

	int64_t ans = 0;

	while (!pq.empty())
	{
		auto [d, i] = pq.top();
		pq.pop();

		int64_t tmp = inf;
		for (int64_t j = 0; j < n; j++)
		{
			if (i == j)
			{
				continue;
			}

			if (rm[j])
			{
				continue;
			}

			tmp = min(tmp, dist(i, j));
		}

		if (tmp == d)
		{
			ans++;
			rm[i] = true;
		}
	}

	cout << ans << endl;

	return 0;
}