counted = {}


def scalar(v1, v2):
    return v1[0] * v2[0] + v1[1] * v2[1]


def scalar_product(a, b, c):
    # a, b, c - координаты точек в формате (x, y)
    # вычислю координаты векторов
    # вектор a -> b
    k1 = tuple(sorted([coord.index(a), coord.index(b)]))
    if k1 in counted:
        Va_b = counted[k1]
    else:
        Va_b = [b[0] - a[0], b[1] - a[1]]
        counted[k1] = Va_b
    # вектор b -> c

    k1 = tuple(sorted([coord.index(c), coord.index(b)]))
    if k1 in counted:
        Vb_c = counted[k1]
    else:
        Vb_c = [c[0] - b[0], c[1] - b[1]]
        counted[k1] = Vb_c

    # вектор c -> a
    k1 = tuple(sorted([coord.index(a), coord.index(c)]))
    if tuple(k1) in counted:
        Vc_a = counted[tuple(k1)]
    else:
        Vc_a = [a[0] - c[0], a[1] - c[1]]
        counted[tuple(k1)] = Vc_a

    return scalar(Va_b, Vb_c) * scalar(Va_b, Vc_a) * scalar(Vb_c, Vc_a) == 0


n = int(input())
coord = []
for i in range(n):
    coord.append(list(map(int, input().split())))

ans = 0
for i in range(n):
    for j in range(i + 1, n):
        for k in range(j + 1, n):
            if scalar_product(coord[i], coord[j], coord[k]):
                ans += 1

print(ans)