#include <fstream>
#include <algorithm>

using namespace std;

ifstream fin("trapez.in");
ofstream fout("trapez.out");

int n, k, dx, dy, l;

long long sol;

pair<int,int> v[1005];

long double panta[1000005];

int main() {
    fin >> n;
    for(int i = 1; i <= n; i++)
    {
        fin >> v[i].first >> v[i].second;
    }
    for(int i = 1; i < n; i++)
        for(int j = i+1; j <= n; j++)
        {
            dx = v[i].first - v[j].first;
            dy = v[i].second - v[j].second;
            if(dx)
                panta[++k]=(long double) dy*1.0/dx;
            else
                l++;
        }
    sol = l * (l-1) / 2;
    sort(panta+1, panta+k+1);
    int ord = 0;
    for(int i = 1; i <= k; i++)
    {
        if(panta[i] == panta[i-1])
            ord++;
        else {
            sol += ord * (ord-1) / 2;
            ord = 1;
        }
    }
    fout << sol << "\n";
    return 0;
}