#include <bits/stdc++.h>

using namespace std;

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

struct punct
{
    double x,y;
} v[1005];
vector <double> p;
int main()
{
    long n,nr=0,c,i,j;
    in >> n;
    for (i = 0; i<n; i++)
        in >> v[i].x >> v[i].y;
    for (i = 0; i<n; i++)
        for (j = i+1; j<n; j++)
            p.push_back((v[j].y-v[i].y)/(v[j].x-v[i].x));
    sort(p.begin(),p.end());
    for (i = 0; i < p.size(); i++)
    {
        c = 1;
        while (p[i] == p[i+1] && i+1<p.size())
        {
            c++;
            i++;
        }
        nr+=(c*(c-1))/2;
    }
    out << nr;
}