import math
import random


mod=random.randint(1<<50,1<<60)
B=random.randint(1<<50,1<<60)
while math.gcd(B,mod)!=1: B=random.randint(1<<50,1<<60)

base = [pow(B,i,mod) for i in range(10)]

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]

    if (x1+x2)%2==0:
      tyuten_x = ((x1+x2)//2, 1)
    else:
      tyuten_x = (x1+x2, 2)

    if (y1+y2)%2==0:
      tyuten_y = ((y1+y2)//2, 1)
    else:
      tyuten_y = (y1+y2, 2)

    # 方向 vec
    vec = [x1-x2, y1-y2]
    if x1-x2==0:
      vec[1] = abs(vec[1])
    if y1-y2==0:
      vec[0] = abs(vec[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)

    a,b=tyuten_x
    c,d=tyuten_y
    e,f=vec

    hush = ((
      a*base[0] + b*base[1] + c*base[2] +
      d*base[3] + e*base[4] + f*base[5]
    )%mod)

    if point_info.get(hush)==None:
      point_info[hush]=0
    point_info[hush]+=1

    # if point_info.get((tyuten, 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]


    if (x1+x2)%2==0:
      tyuten_x = ((x1+x2)//2, 1)
    else:
      tyuten_x = (x1+x2, 2)

    if (y1+y2)%2==0:
      tyuten_y = ((y1+y2)//2, 1)
    else:
      tyuten_y = (y1+y2, 2)

    # 方向 vec
    vec = [x1-x2, y1-y2]
    if x1-x2==0:
      vec[1] = abs(vec[1])
    if y1-y2==0:
      vec[0] = abs(vec[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)

    # a,b=tyuten_x
    # c,d=tyuten_y
    # e,f=vec

    # hush = ((
    #   a*base[0] + b*base[1] + c*base[2] +
    #   d*base[3] + e*base[4] + f*base[5]
    # )%mod)

    # if point_info.get(hush)==None:
    #   point_info[hush]=0
    # point_info[hush]+=1


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

    a,b=tyuten_x
    c,d=tyuten_y
    e,f=inv_vec


    hush = ((
      a*base[0] + b*base[1] + c*base[2] +
      d*base[3] + e*base[4] + f*base[5]
    )%mod)

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

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

# print(point_info)