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 c {
  int x;
  int y;
};
bool comp(struct c p, struct c q) {
  if (p.x > q.x) return false;
  return true;
}
bool comp1(struct c p, struct c q) {
  if (p.y > q.y) return false;
  return true;
}
int binarySearch(int arr[], int l, int r, int x) {
  if (r >= l) {
    int mid = l + (r - l) / 2;
    if (arr[mid] == x) return mid;
    if (arr[mid] > x) return binarySearch(arr, l, mid - 1, x);
    return binarySearch(arr, mid + 1, r, x);
  }
  return -1;
}
int main() {
  int n, c = 0;
  cin >> n;
  struct c a[n];
  int x6[n];
  int y6[n];
  int x7[n];
  int y7[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i].x >> a[i].y;
  }
  sort(a, a + n, comp);
  for (int i = 0; i < n; i++) {
    x6[i] = a[i].x;
    y6[i] = a[i].y;
  }
  for (int i = 0; i < n; i++) {
    x7[i] = a[i].x;
    y7[i] = a[i].y;
  }
  sort(a, a + n, comp1);
  for (int i = 0; i < n; i++) {
    for (int j = i + 1; j < n; j++) {
      int x1 = (a[i].x + a[j].x) / 2;
      int y1 = (a[i].y + a[j].y) / 2;
      if ((a[i].x + a[j].x) % 2 == 0 && (a[i].y + a[j].y) % 2 == 0) {
        int x2 = binarySearch(x6, 0, n, x1);
        if (x2 != -1 && y6[x2] == y1) {
          c++;
        } else {
          int d2 = binarySearch(y7, 0, n, y1);
          if (d2 != -1 && x7[d2] == x1) {
            c++;
          }
        }
      }
    }
  }
  cout << c;
}
