#include <iostream>
#include <fstream>
#include <cmath>
#include <algorithm>

using namespace std;

const int Nmax = 1000;
const double EPS = 1e-9;

#define x first
#define y second

typedef long long ll;

struct Point
{
    int x, y;

    friend istream& operator >> ( istream &f, Point &P )
    {
        f >> P.x >> P.y;
        return f;
    }
};

bool eq( const pair<int,int> &a, const pair<int,int> &b )
{
    return (a.x * b.y == b.x * a.y);
}

bool cmp(const pair<int,int> &a, const pair<int,int> &b) {
    if (a.x * b.y == b.x * a.y) return 0;
    bool r = (a.x * b.y < b.x * a.y);
    if (b.y < 0) r = !r;
    if (a.y < 0) r = !r;
    return r;
}

pair<int,int> slopes[Nmax * Nmax];
Point P[Nmax + 1];
int N;

int main()
{
    ifstream f("trapez.in");
    ofstream g("trapez.out");

    f >> N;

    for ( int i = 1; i <= N; ++i )
            f >> P[i];

    int M = 0;

    for ( int i = 1; i < N; ++i )
            for ( int j = i + 1; j <= N; ++j )
                    slopes[ ++M ] = pair<int,int>( P[i].x - P[j].x, P[i].y - P[j].y );

    sort( slopes + 1, slopes + 1 + M, cmp );

    ll contor = 1;
    ll sol = 0;

    for ( int i = 2; i <= M; ++i )
    {
        if ( eq( slopes[i - 1], slopes[i] ) )
                contor++;
        else
        {
            sol += 1LL * contor * ( contor - 1 ) / 2LL;
            contor = 1;
        }
    }

    sol += 1LL * contor * ( contor - 1 ) / 2LL;

    g << sol << "\n";

    return 0;
}