#include <fstream>
#include <iostream>
#include <cstdio>
#include <string>
#include <stack>
#include <queue>
#include <deque>
#include <cassert>
#include <random>
#include <set>
#include <map>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <sstream>
#include <iomanip>
#include <algorithm>
#include <vector>
#include <list>
#include <tuple>
#include <forward_list>
#include <array>
#include <cstring>
#include <cmath>
#include <complex>
#include <bitset>
#include <climits>
using namespace std;
using LL = long long;
using ULL = unsigned long long;
using LD = long double;
using pii = pair<int, int>;
using pll = pair<LL, LL>;
using pdd = pair<double, double>;
using pld = pair<LD, LD>;


inline bool are_eq(const pll &frac1, const pll &frac2)
{
    return frac1.first * frac2.second == frac1.second * frac2.first;
}


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

    int N;
    cin >> N;

    vector<pii> points(N);
    for (pii &point : points)
    {
        cin >> point.first >> point.second;
    }
    sort(begin(points), end(points));

    vector<pll> slopes;
    for (int i = 0; i < N - 1; ++i)
    {
        for (int j = i + 1; j < N; ++j)
        {
            const int delta_y = points[i].second - points[j].second;
            const int delta_x = points[i].first - points[j].first;
            slopes.push_back({delta_y, delta_x});
        }
    }
    sort(begin(slopes), end(slopes), [](const pll &slope1, const pll &slope2)
    {
        return slope1.first * slope2.second < slope1.second * slope2.first;
    });

    int nr_trapezoids = 0, nr_slopes = (N * (N - 1)) / 2;
    for (int i = 0; i < nr_slopes - 1; ++i)
    {
        int cnt_same = 0;
        for (; i < nr_slopes - 1 && are_eq(slopes[i], slopes[i + 1]); ++i)
        {
            nr_trapezoids += ++cnt_same;
        }
    }

    cout << nr_trapezoids;
}