#include <fstream>
#include <algorithm>
using namespace std;

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

const int MAXN = 1005;
const double INF = 1ll << 40;

int x[MAXN],y[MAXN];
int n;

double pante[MAXN * MAXN];
int k = 0;

void citire()
{
    in >> n;
    for (int i = 1;i <= n;++i)
        in >> x[i] >> y[i];
}

long long rasp = 0;

void prelucrare()
{
    for (int i = 1;i < n;++i)
        for (int j = i + 1;j <= n;++j)
            if (x[j] == x[i])
                pante[++k] = INF;
            else pante[++k] = (double)(y[j] - y[i]) / (x[j] - x[i]);
    sort(pante + 1, pante + k + 1);
    for (int i = 1;i <= k;)
    {
        int j = i;
        while(pante[j] == pante[j + 1])
            ++j;
        rasp += (long long)(j - i + 1) * (j - i) / 2;
        i = j + 1;
    }
}

int main()
{
    citire();
    prelucrare();
    out << rasp;
    return 0;
}