import sys

# sys.setrecursionlimit(1000006)
# sys.set_int_max_str_digits(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
# inf = -1-(-1 << 31)
inf = -1-(-1 << 62)

# md = 10**9+7
md = 998244353

from collections import Counter
from math import gcd

n = II()
xy = LLI(n)
cnt = Counter()

for i in range(n):
    x, y = xy[i]
    for j in range(i):
        s, t = xy[j]
        if x == s:
            cnt[inf, inf, x+s, y+t] += 1
        elif y == t:
            cnt[0, 0, x+s, y+t] += 1
        else:
            a = y-t
            b = x-s
            if a < 0: a, b = -a, -b
            g = gcd(a, b)
            a //= g
            b //= g
            cnt[a, b, x+s, y+t] += 1
ans = 0
for a, b, x, y in cnt:
    c=cnt[a,b,x,y]
    if a == 0:
        ans += cnt[inf, inf, x, y]*c
    elif a == inf:
        ans += cnt[0, 0, x, y]*c
    else:
        if b < 0: a, b = -a, -b
        ans += cnt[b, -a, x, y]*c

print(ans//2)