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 int MAX = 10001;
int n;
struct node {
  int x;
  int y;
} pnt[MAX];
bool operator<(const node& a, const node& b) {
  return a.x < b.x || (a.x == b.x && a.y < b.y);
}
bool search(int l, int r) {
  int t1 = l + 1, t2 = r - 1;
  bool flag = false;
  while (t1 <= t2) {
    int mid = (t1 + t2) / 2;
    if (pnt[l].x + pnt[r].x > 2 * pnt[mid].x) {
      t1 = mid + 1;
    } else if (pnt[l].x + pnt[r].x < 2 * pnt[mid].x) {
      t2 = mid - 1;
    } else {
      flag = true;
      while (t1 - 1 > l && pnt[t1].x == pnt[t1 - 1].x) {
        t1--;
      }
      while (t2 + 1 < r && pnt[t2 + 1].x == pnt[t2].x) {
        t2++;
      }
      while (t1 <= t2) {
        mid = (t1 + t2) / 2;
        if (pnt[l].y + pnt[r].y == 2 * pnt[mid].y) {
          return true;
        } else if (pnt[l].y + pnt[r].y > 2 * pnt[mid].y) {
          t1++;
        } else {
          t2--;
        }
      }
    }
    if (flag) {
      break;
    }
  }
  return false;
}
void solve() {
  long long cnt = 0;
  sort(pnt + 1, pnt + n + 1);
  for (int i = 1; i <= n - 2; i++) {
    for (int j = n; j >= i + 2; j--) {
      if (search(i, j)) {
        cnt++;
      }
    }
  }
  cout << cnt << endl;
}
int main() {
  while (scanf("%d", &n) == 1) {
    for (int i = 1; i <= n; i++) {
      scanf("%d%d", &pnt[i].x, &pnt[i].y);
    }
    solve();
  }
  fclose(stdin);
  fclose(stdout);
  return 0;
}
