#include <fstream>
#include <cmath>
using namespace std;
ifstream f("triang.in");
ofstream g("triang.out");
int n,i,j,z;
double l1,l2,x[2002],y[2002],l3;
long long sol;
int main()
{
    f>>n;
    for (i=1;i<=n;i++)
    f>>x[i]>>y[i];
    for (i=1;i<=n-2;i++)
        for (j=i+1;j<=n-1;j++)
            for (z=j+1;z<=n;z++){
            l1=sqrt((x[j]-x[i])*(x[j]-x[i])+(y[j]-y[i])*(y[j]-y[i])),
                                l2=sqrt((x[z]-x[i])*(x[z]-x[i])+(y[z]-y[i])*(y[z]-y[i])),
                                l3=sqrt((x[z]-x[j])*(x[z]-x[j])+(y[z]-y[j])*(y[z]-y[j]));
            if (-0.001<l1-l2 && l1-l2<0.001 && l1-l3<0.001 && l1-l3>-0.001) sol++;
            }
    g<<sol;
    return 0;
}