#include <bits/stdc++.h>
using std::vector;
using std::array;
using std::pair;
using std::tuple;
using i64 = std::int64_t;
struct Point {
int x, y;
Point(int x = 0, int y = 0) : x(x), y(y) {}
int belongs() const {
if (x >= 0 and y >= 0) return 0;
if (x < 0 and y > 0) return 0;
return 1;
}
friend Point operator+(const Point& p, const Point& q) {
return Point(p.x + q.x, p.y + q.y);
}
friend Point operator-(const Point& p, const Point& q) {
return Point(p.x - q.x, p.y - q.y);
}
friend i64 cross(const Point& p, const Point& q) {
return (i64)p.x * q.y - (i64)p.y * q.x;
}
};
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
int N;
std::cin >> N;
vector<Point> P(N);
for (auto& [x, y] : P) {
std::cin >> x >> y;
}
vector left(N, vector<int>(N));
vector right(N, vector<int>(N));
for (int pivot = 0; pivot < N; ++pivot) {
vector<int> ord;
ord.reserve(N - 1);
for (int i = 0; i < N; ++i) {
if (i != pivot) {
ord.push_back(i);
P[i] = P[i] - P[pivot];
}
}
std::sort(ord.begin(), ord.end(), [&](const int i, const int j) {
if (P[i].belongs() != P[j].belongs()) return P[i].belongs() < P[j].belongs();
return cross(P[i], P[j]) > 0;
});
const auto get = [&](const int i) {
return P[ord[i >= N - 1 ? i - (N - 1) : i]];
};
vector<int> half(2 * (N - 1));
for (int i = 0, r = 0; i < N - 1; ++i) {
while (r < i + N - 1 and cross(get(i), get(r)) >= 0) {
r += 1;
}
half[i] = r;
half[i + N - 1] = r + N - 1;
}
int sum_l = 0, sum_r = 0;
for (int i = 0, r_l = 0, r_r = 0; i < N - 1; ++i) {
while (r_l < half[i]) {
sum_l += half[r_l];
sum_r -= half[r_l];
r_l += 1;
}
while (r_r < i + N - 1) {
sum_r += half[r_r];
r_r += 1;
}
const int above = half[i] - i;
const int below = (N - 1) - above;
left[pivot][ord[i]] = sum_l - above * half[i];
right[pivot][ord[i]] = sum_r - below * (i + N);
sum_l -= half[i];
}
for (const int i : ord) {
P[i] = P[i] + P[pivot];
}
}
int ans = 0;
for (int i = 0; i < N; ++i) {
for (int j = 0; j < i; ++j) {
if (left[i][j] == right[j][i]) {
ans += 1;
}
}
}
std::cout << ans << '\n';
return 0;
}
