#include <fstream>
#include <cstdlib>
#include <map>
#include <iostream>
using namespace std;

typedef pair <double, double> coord;

const int N = 1005;

map <coord, bool> M;
coord v[N];
int n, p;

void get(coord a, coord b) {
    int Y = a.first - b.first, X = a.second - b.second;
    map <coord, bool> :: iterator it1, it2, it3, it4;
    it1 = M.find(make_pair (a.first + X, a.second - Y));
    it2 = M.find(make_pair (b.first + X, b.second - Y));
    it3 = M.find(make_pair (a.first - X, a.second + Y));
    it4 = M.find(make_pair (b.first - X, b.second + Y));
    if (it1 != M.end() && it2 != M.end()) p++;
    if (it3 != M.end() && it4 != M.end()) p++;
}

int main() {
    ifstream fin ("patrate3.in");
    ofstream fout ("patrate3.out");
    fin >> n;
    for (int i = 0; i < n; ++i) {
        fin >> v[i].first >> v[i].second;
        //cout << v[i].first << " " << v[i].second << "\n";
        M[v[i]] = 1;
    }
    for (int i = 1; i < n; ++i)
        for (int j = 0; j < i; ++j)
            get (v[j], v[i]);
    fout << (p >> 2);
}