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

import operator as op
from io import BytesIO
import os
input = BytesIO(os.read(0, os.fstat(0).st_size)).readline

"""
  binary search to find the mid point
"""

def search(arr, left, right, x_mid, y_mid):
  while left <= right:
    mid = (left+right)//2
    curr_x = arr[mid][0]
    curr_y = arr[mid][1]

    if (curr_x == x_mid) and (curr_y == y_mid):
      return 1
    elif curr_x <= x_mid:
      left = mid+1
    else: right = mid-1

  return 0


def main():
  points = int(input())
  arr = [0]*points
  index = 0
  for _ in range(points):
    a, b = map(int, input().split())
    arr[index] = (2*a,2*b)
    index += 1
  # sort on x-coordinate
  arr.sort(key=op.itemgetter(0,1))

  answer = 0
  for left in range(points-2):
    for right in range(left+2, points):
      x_mid = (arr[left][0] + arr[right][0])//2
      y_mid = (arr[left][1] + arr[right][1])//2
      answer += search(arr, left, right, x_mid, y_mid)

  print(answer)


if __name__ == "__main__":
  main()
