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

using namespace std;

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

#define lim 1005
#define inf 0x3f3f3f3f
int n;
struct pct{int x,y;} v[lim];
double m[lim*lim],aux;
long long rez=0;


int main()
{
    fin>>n;
    for(int i=1; i<=n; i++)
        fin>>v[i].x>>v[i].y;

    int k=0;
    for(int i=1; i<n; i++)
        for(int j=i+1; j<=n; j++)
        {
            if(v[j].x-v[i].x)
                aux=( double)((double)(v[j].y-v[i].y) / (double)(v[j].x-v[i].x));
            else
                aux=(v[j].y-v[i].y > 0) ? inf:-inf;
            m[++k]=aux;
        }

    sort(m+1,m+k+1);
    m[++k]=inf;

    int nr=1;
    for (int i=0;i<=k && m[i]!=inf;i++)
    {
      if (m[i]==m[i+1])
        nr++;
      else rez+=nr*(nr-1)/2,nr=1;
    }
    fout<<rez;

    fin.close();
    fout.close();
    return 0;
}