from collections import defaultdict
from collections import Counter
from math import gcd
N = int(input())
XY = [tuple(map(int, input().split())) for _ in range(N)]

d = defaultdict(Counter)
for i in range(N):
   x, y = XY[i]
   for j in range(i+1, N):
      a, b = XY[j]
      dx, dy = a-x, b-y
      if dx < 0:
         dx, dy = -(dx), -(dy)
      if dx == 0 and dy < 0:
         dy = -(dy)
      g = gcd(dx, dy)
      dx, dy = dx//g, dy//g
      center = (x+a, b+y)
      d[center][dx, dy] += 1

ans = 0
for center, C in d.items():
   for (dx, dy), cnt in C.items():
      if dy > 0:
         ndx, ndy = dy, -dx
      else:
         ndx, ndy = -dy, dx
      ans += cnt * C[ndx, ndy]

ans //= 2
print(ans)