#include<iostream>
#include<fstream>
#include<set>
#include<cmath>
using namespace std;

ifstream cit("patrate3.in");
ofstream afis("patrate3.out");

int main()
{
    set<pair<int, int>> perechi;
    pair<int, int> coord[1001];
    int N, x1, x2, x3, x4, y1, y2, y3, y4, nr_pat = 0;
    double x, y;
    cit>>N;
    for(int i = 0; i < N; i++){
        cit>>x>>y;
        coord[i].first = round(x * 10000);
        coord[i].second = round(y * 10000);
        perechi.insert(coord[i]);
    }
    for(int i = 0; i < N; i++){
        for(int j = 0; j < N; j++){
            if(i != j){
                x1 = coord[i].first;
                y1 = coord[i].second;
                x2 = coord[j].first;
                y2 = coord[j].second;
                x3 = y1 - y2 + x1;
                y3 = x2 - x1 + y1;
                x4 = y1 - y2 + x2;
                y4 = x2 - x1 + y2;
                if((perechi.find({x3, y3}) != perechi.end()) && (perechi.find({x4, y4}) != perechi.end())){
                    nr_pat++;
                }
            }
        }
    }
    afis<<nr_pat/4;
    return 0;
}