from collections import defaultdict


def extgcd(a, b):
    if b:
        d, y, x = extgcd(b, a % b)
        y -= (a // b) * x
        return d, x, y
    return a, 1, 0


# 以下modinv
def mod_inv(a, m):
    g, x, y = extgcd(a, m)

    if g != 1:
        raise Exception()

    if x < 0:
        x += m

    return x


p = 998244353
N = int(input())
dat = []
for _ in range(N):
    dat.append(tuple(map(int, input().split())))
dat_set = set(dat)

ans = 0
dic = defaultdict(int)
for i in range(N):
    for j in range(i + 1, N):
        x, y = dat[i]
        x2, y2 = dat[j]
        if x2 - x != 0 and y2 - y != 0:
            mid = (x + x2, y + y2, (x2 - x) * mod_inv(y2 - y, p) % p)
            mid_rev = (x + x2, y + y2, (y - y2) * mod_inv(x2 - x, p) % p)
        elif x2 - x == 0:
            mid = (x + x2, y + y2, p + 1)
            mid_rev = (x + x2, y + y2, -1)
        elif y2 - y == 0:
            mid = (x + x2, y + y2, -1)
            mid_rev = (x + x2, y + y2, p + 1)
        dic[mid] += 1
        ans += dic[mid_rev]
print(ans)