//https://math.stackexchange.com/questions/958381/how-to-find-the-number-of-squares-formed-by-given-lattice-points

#include <iostream>
#include <vector>
#include <fstream>
#include <set>
#include <cmath>
#define N 1001
using namespace std;
ifstream fin("patrate3.in");
ofstream fout("patrate.out");

pair<int, int> v[N];
set<pair<int, int> > p;


int n;
int ct;


void Citire()
{
	int i;
	float x, y;
	fin >> n;
	for (i = 0; i < n; i++)
	{
		fin >> x >> y;
		v[i].first = round(x * (N - 1));
		v[i].second = round(y * (N - 1));
		p.insert(v[i]);
	}
}

void Vf(pair<int, int> p1, pair<int, int> p2)
{
	pair<int, int> p3;
	pair<int, int> p4;

	p3.first = p1.first + (p2.second - p1.second);
	p3.second = p1.second + (p1.first - p2.first);
	
	p4.first = p2.first + (p2.second - p1.second);
	p4.second = p2.second + (p1.first - p2.first);

	
	if (p.find({ p3.first, p3.second }) != p.end() && p.find({ p4.first, p4.second }) != p.end())
	{
		//cout << p3.first <<" "<<p3.second<<" "<<p4.first<<" "<<p4.second << "\n";
		ct++;
	}


}
void Solve()
{
	int i, j;

	for (i = 0; i < n; i++)
		for (j = 0; j < n; j++)
			if (i != j)
				Vf(v[i], v[j]);

}

int main()
{
	Citire();
	Solve();

	fout << ct / 4;
	return 0;
}