ĐA GIÁC BAO

#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#define task ""
using namespace std;
using ll = long long;
using ld = long double;

const int N = 2.5e3 + 2;
int n;
struct Vector
{
    ll x, y;
    Vector(int x = 0, int y = 0)
    {
        this->x = x;
        this->y = y;
    }
    Vector operator-(const Vector &a) const
    {
        Vector ans;
        ans.x = x - a.x;
        ans.y = y - a.y;
        return ans;
    }
    ll operator*(const Vector &a)
    {
        return x * a.y - y * a.x;
    }
    bool operator<(const Vector &a) const
    {
        bool ck1 = x < 0 || (x == 0 && y < 0),
             ck2 = a.x < 0 || (a.x == 0 && a.y < 0);
        if (ck1 != ck2)
            return ck1 < ck2;
        return (x * a.y - y * a.x) > 0;
    }
} a[N];

void Read()
{
    cin >> n;
    for (int i = 1; i <= n; ++i)
        cin >> a[i].x >> a[i].y;
}

ll C3(ll v)
{
    return v * (v - 1) * (v - 2) / 6;
}

ll C5(ll v)
{
    return v * (v - 1) * (v - 2) * (v - 3) * (v - 4) / 120;
}

void Solve()
{
    ll ans(0);
    for (int i = 1; i <= n; ++i)
    {
        // cout << i << ":\n";
        vector<Vector> s;
        for (int j = 1; j <= n; ++j)
            if (i != j)
                s.push_back(a[j] - a[i]);
        sort(s.begin(), s.end());
        int t = 0;
        for (int j = 0; j < (int)s.size(); ++j)
        {
            while (t < j + (int)s.size() && s[j] * s[t % s.size()] >= 0)
                ++t;
            //cout << j << " " << t << "\n";
            ans += C3(t - j - 1);
        }
    }
    cout << C5(n) * 5 - ans;
}

int32_t main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    if (fopen(task ".INP", "r"))
    {
        freopen(task ".INP", "r", stdin);
        freopen(task ".OUT", "w", stdout);
    }
    Read();
    Solve();
}