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;
struct Point {
  int x, y;
} points[3000];
int n, res;
double tX, tY;
bool comp(Point a, Point b) {
  if (a.x == b.x) {
    return a.y < b.y;
  }
  return a.x < b.x;
}
int binarySearch(int low, int high, double targetX, double targetY) {
  int mid = (low + high) / 2;
  if (low == high) {
    return -1;
  }
  if (points[mid].x == targetX && points[mid].y == targetY) {
    return mid;
  }
  if (targetX < points[mid].x ||
      (targetX == points[mid].x && targetY < points[mid].y)) {
    binarySearch(low, mid - 1, targetX, targetY);
  } else if (targetX > points[mid].x ||
             (targetX == points[mid].x && targetY > points[mid].y)) {
    binarySearch(mid, high, targetX, targetY);
  }
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cin >> n;
  for (int i = 0; i < n; ++i) {
    cin >> points[i].x >> points[i].y;
  }
  int ans = 0;
  sort(points, points + n, comp);
  for (int i = 0; i < n; ++i) {
    for (int j = i + 1; j < n; ++j) {
      tX = (points[i].x + points[j].x) / double(2);
      tY = (points[i].y + points[j].y) / double(2);
      res = binarySearch(0, n, tX, tY);
      if (res > 0 && res != i && res != j) {
        cout << i << " " << j << '\n';
        cout << tX << " " << tY << '\n';
        ++ans;
      }
    }
  }
  cout << ans << "\n";
}
