#include <iostream>
#include <cmath>
#include <fstream>

using namespace std;
ifstream f("triang.in");
ofstream g("triang.out");

double distanta(double x1, double y1, double x2, double y2)
{
    double rezultat,xp,yp;
    xp=(x2-x1)*(x2-x1);
    yp=(y2-y1)*(y2-y1);
    rezultat=sqrt(xp+yp);
return rezultat;
}
int n,i,j,p,cnt,nr;
double eroare=0.001,distanta1,distanta2,distanta3;
struct coordonate
{
    double x,y;
}v[1501];
int main()
{
f>>n;
for(i=1;i<=n;i++)
    f>>v[i].x>>v[i].y;

for(i=1;i<=n-2;i++)
    for(j=i+1;j<=n-1;j++)
         for(p=j+1;p<=n;p++)
         {
             cnt=0;
             distanta1=distanta(v[i].x,v[i].y,v[j].x,v[j].y);
             distanta2=distanta(v[j].x,v[j].y,v[p].x,v[p].y);
             distanta3=distanta(v[i].x,v[i].y,v[p].x,v[p].y);

             if(abs(distanta1-distanta2)<=eroare)
                 cnt++;
             if(abs(distanta3-distanta2)<=eroare)
                cnt++;
             if(abs(distanta3-distanta1)<=eroare)
                cnt++;

             if(cnt==3)
                nr++;
         }


g<<nr;

    return 0;
}