#include <iostream>
#include <fstream>
#include <map>
#include <string>
#include <cmath>

std::ifstream f("patrate3.in");
std::ofstream g("patrate3.out");
 

std::map<std::pair<int, int>, bool> map;
struct {
	int x, y;
}patrate[1000];

int n;

//void print(int x, int y)
//{
//	std::cout << "(" << x << ", " << y << ") ";
//}

int main()
{
	f >> n;
	
	float x, y;
	for (int i = 0; i < n; ++i)
	{
		f >> x >> y;

		patrate[i].x = round(x * 10000.0f);
		patrate[i].y = round(y * 10000.0f);

		map[{patrate[i].x, patrate[i].y}] = 1;
	}

	long long total = 0;

	int x1, y1, x2, y2, x3, y3, x4, y4;
	for (int i = 0; i < n; ++i)
		for (int j = i + 1; j < n; ++j)
		{
			x1 = patrate[i].x;
			y1 = patrate[i].y;
			x2 = patrate[j].x;
			y2 = patrate[j].y;
			//std::cout << x1 << ' ' << y1 << " si " << x2 << ' ' << y2 << '\n';
			//  pct 1  ________ pct 4
			//         |	   |
			//         |       |
			//         |_______|
			//  pct 2           pct 3

			// rotesc pct 1 in jurul pct 2 cu -90 grade (in sens trigonometric), (adica din x1, y1 scad x2, y2, rotesc (x,y) -> (y, -x) , si dupa adun x2, y2 inapoi)
			x3 = y1 - y2 + x2;
			y3 = x2 - x1 + y2;

			// fac acelasi lucru pt pct 2 doar ca in rotesc cu 90 grade (x, y) -> (-y, x)
			x4 = y1 - y2 + x1;
			y4 = x2 - x1 + y1;

			total += (map[{x3, y3}] & map[{x4, y4}]);
		}

	g << total / 2; // impartit la 2 pt ca numara de doua ori acelasi patrat o data pt perechea (pct1 si pct2) si o data pt perechea (pct1 si pct4)
}