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 static int inf = 10000000;
const static int mod = 1000000007;
bool p[2222][2222];
bool Get(int x, int y) { return p[x + 1000][y + 1000]; }
void Set(int x, int y, bool val) { p[x + 1000][y + 1000] = val; }
int abs_i(int x) {
  if (x < 0) {
    return -x;
  }
  return x;
}
int main() {
  int n;
  while (cin >> n) {
    for (int i = 0; i < (int)(2222); i++) {
      for (int j = 0; j < (int)(2222); j++) {
        p[i][j] = false;
      }
    }
    vector<int> x(n);
    vector<int> y(n);
    for (int i = 0; i < (int)(n); i++) {
      cin >> x[i];
      cin >> y[i];
      Set(x[i], y[i], true);
    }
    int ans = 0;
    for (int i = 0; i < (int)(n); i++) {
      for (int j = i + 1; j < n; ++j) {
        if (abs_i(x[i] - x[j]) % 2 == 0 && abs_i(y[i] - y[j]) % 2 == 0) {
          int xx = (x[i] + x[j]) / 2;
          int yy = (y[i] + y[j]) / 2;
          if (Get(xx, yy)) {
            ++ans;
          }
        }
      }
    }
    cout << ans << endl;
  }
  return 0;
}
