#include<iostream>
#include<fstream>
#include<algorithm>
using namespace std;

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

double v[1010030];
int n, k;

struct coordonate_punct
{
    double x, y;
} p[1005];

int main()
{
    int i, j;
    f >> n;
    for(i = 1; i <= n; i++)
        f >> p[i].x >> p[i].y;
    for( i = 1; i <= n; i++)
        for( j = i + 1; j <= n; j++)
        {
            v[++k]=(p[j].x - p[i].x) / (p[j].y-p[i].y);
        }
    sort( v + 1, v + k + 1);
    int rezultat = 0;

    for( i = 1; i <= k; i++)
    {
        int nr  = 1;
        while( i< k && v[i] == v[i+1])
        {
            i++;
            nr++;
        }
        rezultat =  rezultat + (nr * (nr-1)) / 2;
    }
    g << rezultat;

    return 0;
}