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;
long px, py, x[3001], y[3001], temp, n, i, res, j, tx, ty, first, last, mid;
bool p;
void quick(long l1, long r1) {
  long i1, j1;
  if (l1 >= r1) return;
  px = x[(l1 + r1) >> 1];
  py = y[(l1 + r1) >> 1];
  i1 = l1;
  j1 = r1;
  do {
    while (x[i1] < px || (x[i1] == px && y[i1] < py)) i1++;
    while (x[j1] > px || (x[j1] == px && y[j1] > py)) j1--;
    if (i1 <= j1) {
      if (i1 < j1) {
        temp = x[i1];
        x[i1] = x[j1];
        x[j1] = temp;
        temp = y[i1];
        y[i1] = y[j1];
        y[j1] = temp;
      }
      i1++;
      j1--;
    }
  } while (i1 <= j1);
  quick(l1, j1);
  quick(i1, r1);
}
int main() {
  cin >> n;
  for (i = 1; i <= n; i++) cin >> x[i] >> y[i];
  quick(1, n);
  res = 0;
  for (i = 1; i <= n - 1; i++)
    for (j = i + 1; j <= n; j++)
      if (((x[i] + x[j]) % 2) == 0 && ((y[i] + y[j]) % 2) == 0) {
        tx = (x[i] + x[j]) >> 1;
        ty = (y[i] + y[j]) >> 1;
        first = 0;
        last = n + 1;
        p = false;
        while (first + 1 < last && p == false) {
          mid = (first + last) >> 1;
          if (x[mid] < tx || (x[mid] == tx && y[mid] < ty))
            first = mid;
          else
            last = mid;
          if (x[mid] == tx && y[mid] == ty) p = true;
        }
        if (p == true) res++;
      }
  cout << res;
}
