10
-2 1
2 -2
-1 -2
0 0
2 -1
0 -2
2 2
0 2
-1 -1
1 -2
 40
-8 24
2 -1
1 -18
72 -70
5 -4
-308 436
-19 40
36 -35
-178 265
-1 2
-7 30
-1 0
3 -2
200 -285
17 -16
-35 74
0 -4
-86 106
-1 4
-7 6
0 1
-5 4
-2 3
6 -5
-4 5
181 -262
76 -118
0 0
-7 18
-58 104
-5 6
-6 12
-3 4
1 0
11 -10
-86 130
-3 6
153 -236
-183 270
-33 64
 5
0 -1
0 -2
0 -3
0 -4
0 -5
 10
0 1
-1 -1
1 1
-1 0
1 -1
-2 -1
-2 2
-2 0
0 -2
0 -1
 20
-1 18
-2 5
-5 4
2 -33
9 -18
0 0
11 -22
2 0
-1 2
-4 41
1 6
1 -2
6 -12
0 1
-3 6
3 -6
3 -8
-1 4
2 -5
1 0
 10
2 1
-1 0
-2 -1
-1 1
0 2
2 -2
0 0
-2 -2
0 -2
-2 1
 20
-3 -3
0 4
-3 1
1 1
-1 2
-4 4
3 -1
-3 0
0 2
4 0
2 3
2 4
4 -3
-4 3
-1 1
1 3
-2 4
1 -2
1 -1
3 0
 3
0 0
0 -1
0 1
 10
2 1
-1 1
0 0
-3 1
-2 -3
-1 -2
-1 -1
1 2
3 -2
0 -2
 3
3 3
1 2
1 1
 4
0 0
1 0
2 0
3 0
 9
1 1
1 0
0 1
0 0
-1 0
-1 1
-1 -1
1 -1
0 -1
 7
1 1
-1 -1
1 0
0 1
-1 0
0 -1
0 0

4
 57
 4
 5
 21
 4
 10
 1
 1
 0
 2
 8
 3

#include <bits/stdc++.h>
using namespace std;
const long long Long_max = numeric_limits<long long>::max();
const int Int_max = numeric_limits<int>::max();
void File_input(string pathIn) { freopen(pathIn.c_str(), "r", stdin); }
void File_output(string pathOut) { freopen(pathOut.c_str(), "w", stdout); }
int msg() {
  srand(time(0));
  vector<string> st = {"Wish everyone high ratings!", "Good luck!", "Have fun!",
                       "Please, read all the problems!", "Go Go fight!"};
  cerr << st[rand() % (int)st.size()];
  return 0;
}
void FastInputOutput() {
  ios_base ::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
int t;
vector<pair<double, double> > pre;
map<pair<double, double>, bool> in;
double x, y;
int main() {
  FastInputOutput();
  cin >> t;
  while (t--) {
    cin >> x >> y;
    pre.push_back({x, y});
    in[{x, y}] = 1;
  }
  sort(pre.begin(), pre.end());
  int cn = 0;
  for (int i = 0; i < (int)pre.size() / 2; i++) {
    for (int j = i + 1; j < (int)pre.size(); j++) {
      if (i == j) continue;
      double midX = pre[i].first + pre[j].first;
      midX /= 2;
      double midY = pre[i].second + pre[j].second;
      midY /= 2;
      cn += in[{midX, midY}];
    }
  }
  cout << cn;
}
