#include <fstream>
#include <unordered_map>


struct point
{
    int x, y;
};


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

int main()
{

    std::ifstream fin("trapez.in");
    fin>>n;
    for (int i = 0; i < n; ++i)
    {
            fin>>a>>b;
            *(pts+i) = point{a,b};
    }
    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;

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

}