#include<iostream.h>
#include<fstream.h>
#include<iomanip.h>
#include<math.h>
main()
{
fstream f("trapez.in",ios::in), g("trapez.out",ios::out);
long x[100],y[100];
int k,n,i,j,a,b;
f>>n;
for (i=1;i<=n;i++) f>>x[i]; f>>y[i];
a=0;b=0;k=0;
while (a<n) {a++;
while (b<n) {b++;
if (a!=b) {
for (i=1;i<n;i++)
for (j=i+1;j<=n;j++)
if ((y[b]-y[a])/(x[b]-x[a])==(y[j]-y[i])/(x[j]-x[i])) k++;
}
}             }

g<<k;
}