#include <fstream>
#include <vector>
#include <algorithm>

using namespace std;

ifstream f("trapez.in");
ofstream g("trapez.out");

typedef pair < int, int > PII;

const int NMAX = 1e3 + 5;

int N;
PII A[NMAX];

vector < long double > V;

long long ans = 0;

static inline void Read ()
{
    f.tie(nullptr);

    f >> N;

    for(int i = 1; i <= N; ++i)
        f >> A[i].first >> A[i].second;

    return;
}

static inline void Precalculation ()
{
    for(int i = 1; i < N; ++i)
        for(int j = i + 1; j <= N; ++j)
        {
            long double Numa = A[j].second - A[i].second;
            long long Numb = A[j].first - A[i].first;

            long double X = ((Numb) ? (Numa / Numb) : 1e9);

            V.push_back(X);
        }

    return;
}

static inline void Solve ()
{
    sort(V.begin(), V.end());

    int Now = 1;

    for(int i = 1; i < (int)V.size(); ++i)
    {
        if(V[i] == V[i - 1])
            ++Now;
        else
        {
            if(Now > 1)
                ans += 1LL * (Now * (Now - 1LL)) / 2LL;

            Now = 1;
        }
    }

    if(Now > 1)
        ans += 1LL * (Now * (Now - 1LL)) / 2LL;

    g << ans << '\n';

    return;
}

int main()
{
    Read();

    Precalculation();

    Solve();

    return 0;
}