#include <iostream>
#include <fstream>
#include <set>
#include <cmath>
using namespace std;
ifstream f("patrate3.in");
ofstream g("patrate3.out");

struct punct
{
    int x,y;
};

pair <int, int>  v[1001];
set<pair <int, int> > s;

bool estePatrat(pair <int, int> A, pair <int, int> B){
    int dx = A.first - B.first, dy = B.second - A.second;
    if(s.find({A.first + dy, A.second + dx}) != s.end())
        if(s.find({B.first + dy, B.second + dx}) != s.end())
            return true;
    return false;
}

int main()
{
    int n, c=0;
    double xx, yy;
    f >> n;
    for(int i = 1; i <= n; i++)
    {
        f >> xx >> yy;
        v[i].first = round(xx * 10000);
        v[i].second = round(yy * 10000);
        s.insert(v[i]);
   }
    for(int i = 1; i <= n ; i++)
        for(int j = 1 ; j <= n ; j++)
            if(i != j && estePatrat(v[i], v[j]))
                c++;
    g << c / 4;
    return 0;
}