#include <fstream>
#include <cmath>
#include <algorithm>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
double nr[1000001];
const int INF=2000000001;
class POINT
{
   private:
   double  x,y;
   public:
   POINT()
   {x=0;y=0;}
   void set(double a,double b)
   {x=a;y=b;}
   friend double panta(const POINT P1,const POINT P2)
   {
     if(P1.x-P2.x==0)
        return INF;
    else
      return ((P1.y-P2.y)/(P1.x-P2.x));
   }
};
int main()
{
    POINT v[1001];
    int i,n,x1,y1,j,cnt=0,paralele=0;
    fin>>n;
    for(i=1;i<=n;i++)
        {
          fin>>x1>>y1;
          v[i].set(x1,y1);
        }
    for(i=1;i<=n-1;i++)
        for(j=i+1;j<=n;j++)
            { cnt++;
              nr[cnt]=panta(v[i],v[j]);
            }
    sort(nr+1,nr+cnt+1);
    for(i=2;i<=cnt;i++)
        if(nr[i]==nr[i-1])
           paralele++;
    fout<<(paralele*(paralele+1))/2;
    return 0;
}