#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>;


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;
    }

    vector<pii> slopes;
    for (int i = 0; i < N - 1; ++i)
    {
        for (int j = i + 1; j < N; ++j)
        {
            slopes.push_back({points[i].second - points[j].second, points[i].first - points[j].first});
        }
    }

    int nr_equal_slopes = 0;
    for (int i = 0; i < (N * (N - 1)) / 2 - 1; ++i)
    {
        for (int j = i + 1; j < (N * (N - 1)) / 2; ++j)
        {
            pll slope1 = slopes[i], slope2 = slopes[j];

            if (slope1.first * slope2.second == slope1.second * slope2.first)
            {
                nr_equal_slopes += 2;
            }
        }
    }

    cout << nr_equal_slopes / 2;
}