#include <bits/stdc++.h>
#define INF 2001
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
struct wow
{
    double x,y;
}v[1005];
int q;long double nani[1000005];
int cautbin (int val)
{
    int st=1,dr=q,mij,sol;
    while (st<=dr)
    {
        mij=(st+dr)/2;
        if (nani[mij]<=val)
        {
            sol=mij;
            st=mij+1;
        }
        else
        {
            dr=mij-1;
        }
    }
    return sol;
}
int n,i,sum,j,nr;
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==0)
            {
                nani[++q]=INF;
            }
            else
            {
                nani[++q]=(v[i].y-v[j].y)/(v[i].x-v[j].x);
            }
        }
    }
    sort (nani+1,nani+q+1);
    nr=1;
    for (i=2;i<=q;i++)
    {
        if (nani[i]==nani[i-1])
        {
            nr++;
        }
        else
        {
            sum+=(nr*(nr-1))/2;
            nr=1;
        }
    }
    sum+=(nr*(nr-1))/2;
    g<<sum;
    return 0;
}