#include <fstream>
#include <unordered_map>


struct point
{
    int x, y;
};



int main()
{

    int n, a, b;
    point pts[1000];
    std::unordered_map<double, int> test;
    long long result = 0;


    std::ifstream fin("trapez.in");
    fin>>n;
    for (int i = 0; i < n; ++i)
    {
            fin>>a>>b;
            pts[i] = point{a,b};
    }
    fin.close();
    for (int i = 0; i < n; ++i)
    {
        for (int j = i+1; i < n-1; ++j)
        {

            a = pts[i].x - pts[j].x;
            b = pts[i].y - pts[j].y;
            int test2 = test[((double)b/(double)a)];
            result+=test2;
            test[((double)b/(double)a)] = test2+1;

        }
    }
    std::ofstream fout("trapez.out");
    fout << result;
    fout.close();

}