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

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

void ReadFile();
void Sol();
long long factorial(int fact);

const int MaxN = 1001, MaxX = 500000, inf = 0x3f3f3f3f;
int ii[MaxN], jj[MaxN], n, contor = 1;
double panta[MaxX];

int main()
{
    ReadFile();
    Sol();
}

void ReadFile()
{
    fin >> n;
    for (int i = 1; i <= n; ++i)
        fin >> ii[i] >> jj[i];
}

void Sol()
{
    for (int i = 1; i < n; ++i)
        for (int j = i + 1; j <= n; ++j)
        {
            if (ii[i] == ii[j])
                panta[contor++] = inf;
            else
                panta[contor++] = double(jj[i] - jj[j]) / double(ii[i] - ii[j]);
        }
    sort (panta + 1, panta + contor - 1);

    unsigned long long contorr = 0, fact = 0;
    for (int i = 1; i < contor - 1; ++i)
    {
        fact = 1;
        for (int j = i; panta[j] == panta[j + 1]; ++j)
        {
            fact++;
        }
        if (fact != 1)
            contorr += factorial(fact - 1);
    }

    fout << contorr;


}

long long factorial(int fact)
{
    if (fact == 0)
        return 0;
    return fact + factorial(fact - 1);
}