#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>

#define EPS 1e-6
#define APPROX(a, b) (abs((a) - (b)) <= EPS)

typedef std::pair<double, double> Point;
bool operator== (const Point& left, const Point& right) {
  return APPROX(left.first, right.first) && APPROX(left.second, right.second);
}

bool operator< (const Point& left, const Point& right) {
  if (APPROX(left.first, right.first)) {
    return left.second < right.second;
  } else {
    return left.first < right.first;
  }
}

bool findp(std::vector<Point >& v, Point p) {
  int li = 0, lf = v.size() - 1;
  while (li <= lf) {
    int m = (li + lf) / 2;
    if (v[m] == p) {
      return true;
    } else if (v[m] < p) {
      li = m + 1;
    } else {
      lf = m - 1;
    }
  }

  return false;
}

int main()
{
  std::ifstream in("patrate3.in");
  std::ofstream out("patrate3.out");

  int n;
  in >> n;
  std::vector<Point> v;
  for (int i = 0; i < n; ++i) {
    Point p;
    in >> p.first >> p.second;
    v.push_back(p);
  }

  std::sort(v.begin(), v.end());

  int sol = 0;
  for (int i = 0; i < v.size(); ++i) {
    for (int j = i + 1; j < v.size(); ++j) {
      double d = v[j].second - v[i].second;
      double D = v[j].first - v[i].first;
      if (findp(v, Point(v[i].first - d, v[i].second + D)) &&
          findp(v, Point(v[j].first - d, v[j].second + D))) {
        sol++;
      }
    }
  }

  out << sol / 2 << std::endl;

  in.close();
  out.close();

  return 0;
}