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 s {
  int x, y;
};
vector<struct s> v;
int n;
bool compare(const struct s &a, const struct s &b) {
  if (a.x == b.x) return a.y < b.y;
  return a.x < b.x;
}
int bsrch(int lo, int hi, int key1, int key2) {
  int mid;
  while (lo <= hi) {
    mid = (lo + hi) / 2;
    if (v[mid].x == key1 && v[mid].y == key2)
      return mid;
    else if (v[mid].x < key1 || (v[mid].x == key1 && v[mid].y < key2))
      lo = mid + 1;
    else
      hi = mid - 1;
  }
  return -1;
}
int main() {
  scanf("%d", &n);
  struct s temp;
  for (int i = 0; i < n; i++) {
    scanf("%d %d", &temp.x, &temp.y);
    v.push_back(temp);
  }
  sort(v.begin(), v.end(), compare);
  int counter = 0;
  for (int i = 0; i < n - 2; i++) {
    for (int j = i + 2; j < n; j++) {
      int p = v[i].x + v[j].x, q = v[i].y + v[j].y;
      if (p % 2 == 0 && q % 2 == 0) {
        p >>= 1;
        q >>= 1;
        int d = bsrch(i + 1, j - 1, p, q);
        if (d == -1)
          continue;
        else
          ++counter;
      }
    }
  }
  printf("%d\n", counter);
  return 0;
}
