import math

ans = 0

N=int(input())
P = []
for i in range(N):
  x, y = map(int, input().split())
  P.append((x, y))

point_info = dict()

for i in range(N):
  for j in range(N):
    if P[i]==P[j]: continue
    x1, y1 = P[i]
    x2, y2 = P[j]

    tyuten_x = [x1+x2, 2]
    if (x1+x2)%2==0:
      tyuten_x = [(x1+x2)//2, 1]
    tyuten_x = tuple(tyuten_x)

    tyuten_y = [y1+y2, 2]
    if (y1+y2)%2==0:
      tyuten_y = [(y1+y2)//2, 1]
    tyuten_y = tuple(tyuten_y)

    tyuten = (tyuten_x, tyuten_y)

    # 方向 vec
    vec = [x1-x2, y1-y2]
    if x1-x2==0: vec[0]=0
    if y1-y2==0: vec[1]=0
    if vec[1]<0: vec[0]*=-1; vec[1]*=-1
    g = math.gcd(abs(vec[0]), abs(vec[1]))
    vec[0]//=g; vec[1]//=g

    vec = tuple(vec)

    if point_info.get(tyuten)==None:
      point_info[tyuten]=dict()
    if point_info[tyuten].get(vec)==None:
      point_info[tyuten][vec]=0
    point_info[tyuten][vec] += 1

# for key in point_info:
#   point_info[key]=dict(point_info[key])

# point_info = dict(point_info)

# for key in point_info:
#   print(key, point_info[key])

for i in range(N):
  for j in range(N):
    if P[i]==P[j]: continue
    x1, y1 = P[i]
    x2, y2 = P[j]

    tyuten_x = [x1+x2, 2]
    if (x1+x2)%2==0:
      tyuten_x = [(x1+x2)//2, 1]
    tyuten_x = tuple(tyuten_x)

    tyuten_y = [y1+y2, 2]
    if (y1+y2)%2==0:
      tyuten_y = [(y1+y2)//2, 1]
    tyuten_y = tuple(tyuten_y)

    tyuten = (tyuten_x, tyuten_y)

    # 方向 vec
    vec = [x1-x2, y1-y2]
    if x1-x2==0: vec[0]=0
    if y1-y2==0: vec[1]=0
    if vec[1]<0: vec[0]*=-1; vec[1]*=-1
    g = math.gcd(abs(vec[0]), abs(vec[1]))
    vec[0]//=g; vec[1]//=g

    vec = tuple(vec)


    inv_vec = [vec[1], vec[0]*(-1)]
    if inv_vec[1]<0:
      inv_vec[0]*=-1; inv_vec[1]*=-1
    inv_vec = tuple(inv_vec)

    if point_info.get(tyuten) != None:
      if point_info[tyuten].get(inv_vec) != None:
        ans += point_info[tyuten][inv_vec]

print(ans//8 + 1 if ans!=0 else 0)