#include <fstream>
#include <algorithm>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <iostream>
#include <string.h>
#include <vector>
#include <queue>
#include <stack>
using namespace std;

#define eps 0.0001

/**************** GLOBALS ****************/
struct punct {
    float x, y;
    friend bool operator < (const punct &a, const punct &b) {
        if (a.x + eps < b.x || (a.x - b.x > -eps && a.x - b.x < eps  && a.y + eps < b.y))
            return 1;
        return 0;
    }
}p, p1, p2;

vector<punct> v;
int i, j, n, result;
float dx, dy;


/***************** MAIN *****************/
int main() {
    ifstream fin("patrate3.in");
    ofstream fout("patrate3.out");

    // Read
    fin >> n;
    for (i = 1; i <= n; i++) {
        fin >> p.x >> p.y;
        v.push_back(p);
    }


    // Compute
    sort(v.begin(), v.end());

    for (i = 0; i < n; i++)
        for (j = i + 1; j < n; j++) {
            p.x = (v.at(i).x + v.at(j).x) / 2;
            p.y = (v.at(i).y + v.at(j).y) / 2;

            dx = fabs(p.x - v.at(i).x);
            dy = fabs(p.y - v.at(i).y);

            if (v.at(i).y + eps < v.at(j).y) {
                p1.x = p.x + dy;
                p1.y = p.y - dx;
                p2.x = p.x - dy;
                p2.y = p.y + dx;
            } else {
                p1.x = p.x - dy;
                p1.y = p.y - dx;
                p2.x = p.x + dy;
                p2.y = p.y + dx;
            }

            if (binary_search(v.begin(), v.end(), p1) && binary_search(v.begin(), v.end(), p2))
                result++;
        }


    // Print
    fout << result / 2;
    cout << result / 2;
}