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

using namespace std;

const int NMAX = 1000;

pair<long long, long long> vec[1 + NMAX];

vector<pair<long long, long long>> slopes;

bool comp(const pair<long long, long long>& a, const pair<long long, long long>& b)
{
    return a.first * b.second < b.first * a.second;
}

bool egale(pair<long long, long long> a, pair<long long, long long> b)
{
    return a.first * b.second == b.first * a.second;
}

int main()
{
    ifstream in("trapez.in");
    ofstream out("trapez.out");
    int n;

    in >> n;
    for (int i = 1; i <= n; i++)
    {
        in >> vec[i].first >> vec[i].second;

        for (int j = 1; j < i; j++)
        {
            slopes.push_back(make_pair(vec[i].second - vec[j].second, vec[i].first - vec[j].first));
        }
    }

    sort(slopes.begin(), slopes.end(), comp);

    long long sol = 0;
    long long current = 1;
    for (int i = 1; i < slopes.size(); i++)
    {
        if (egale(slopes[i], slopes[i - 1]))
        {
            current++;
        }
        else
        {
            sol += current * (current - 1) / 2;
            current = 1;
        }
    }

    sol += current * (current - 1) / 2;

    out << sol << '\n';

    return 0;
}