#include <iostream>
#include <algorithm>
#include <fstream>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
int x[1001],y[1001],pant[2000];
int i,j,trp=1,nr,rez,n;
int main()
{
    f>>n;
    for(i=0;i<n;i++)
        f>>x[i]>>y[i];

    for(i=0;i<n-1;i++)
        for(j=i+1;j<n;j++)
        if(i!=j)
         {

            if(x[j]-x[i]==0)
                pant[nr]=2e9,nr++;

            else
             pant[nr]=(y[j]-y[i])/(x[j]-x[i]),nr++;
        }

    sort(pant,pant+nr);

    for(i=1;i<n;i++)
    {
      if(pant[i]==pant[i-1])
      trp++;

      else
      {
        rez+=(trp*(trp-1))/2;
        trp++;
      }


    }
    rez+=(trp*(trp-1))/2;
    g<<rez;
    return 0;
}