#include <bits/stdc++.h>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
int n,i,j,rez,nr,  x[1001], y[1001],k;
long double pante[1000001], panta;
struct punct {

    long x, y;
}v[10001];
int main()
{
    f >> n;
    for ( i = 1; i <= n; i++ )
        f >> v[i].x >> v[i].y;
    for ( i = 1; i <= n; i++)
        for ( j = i+1; j <= n; j++)
            if ( v[i].x == v[j].x ) pante[++k] = INT_MAX;
        else
            {panta = (1.0 * (v[j].y - v[i].y)) / (1.0 *(v[j].x - v[i].x));
            pante[++k] = panta; }
    sort (pante + 1, pante + k + 1);
    /*for (i=1; i<=k;i++)
        cout<<pante[i]<<" ";*/
    nr = 1;
    for ( i = 1; i <= k; i++)
        if( pante[i] == pante[i+1] )
            nr++;
        else
        {
            rez += ((nr*(nr-1))/2);
            nr = 1;
        }

    g << rez;

    return 0;
}