#include <iostream>
#include<algorithm>
#include<fstream>
#include<vector>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
int poz[1001],n,i,x[1001],y[1001],j,l,nr=1,cnt;
vector<double>p;
int main()
{
   f>>n;
   for(i=1;i<=n;i++) f>>x[i]>>y[i];
   for(i=1;i<n;i++)
   for(j=i+1;j<=n;j++)
       p.push_back((double)(((double)((double)y[i]-(double)y[j]))/((double)((double)x[i]-(double)x[j]))));
   int l=n*(n-1)/2;
   sort(p.begin(),p.end());
   for(i=0;i<l;i++)
   {
       //simplifica(i);
       if((i>0) && p[i]==p[i-1])
           nr++;
       else
       {
           cnt+=nr*(nr-1)/2;
           nr=1;
       }
   }
   cnt+=nr*(nr-1)/2;
   g<<cnt;

}