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;
int xpos[2000], xneg[2000], ypos[2000], yneg[2000];
int main() {
  int t, i, x, y, a, j, b, cnt = 0, ar[3009][5];
  cin >> t;
  for (i = 0; i < t; ++i) {
    cin >> a >> b;
    if (a < 0) {
      xneg[abs(a)]++;
    } else {
      xpos[a]++;
    }
    if (b < 0) {
      yneg[abs(b)]++;
    } else {
      ypos[b]++;
    }
    ar[i][0] = a;
    ar[i][1] = b;
  }
  for (i = 0; i < t; ++i) {
    for (j = i + 1; j < t; ++j) {
      x = ar[i][0] + ar[j][0];
      y = ar[i][1] + ar[j][1];
      if (x % 2 == 0 && y % 2 == 0) {
        if (x < 0) {
          if (xneg[abs(x / 2)] > 0) {
            if (y < 0) {
              if (yneg[abs(y / 2)] > 0) {
                cnt++;
              }
            } else {
              if (ypos[y / 2] > 0) {
                cnt++;
              }
            }
          }
        } else {
          if (xpos[x / 2] > 0) {
            if (y < 0) {
              if (yneg[abs(y / 2)] > 0) {
                cnt++;
              }
            } else {
              if (ypos[y / 2] > 0) {
                cnt++;
              }
            }
          }
        }
      }
    }
  }
  cout << cnt << endl;
  return 0;
}
