#include<fstream>
#include<cmath>
#include<algorithm>
using namespace std;

struct pct
{
	double x,y;
};

const double t=1e-14;
long long s,l;
double a[1000000];
pct v[1001];
int i,n,m,j;

bool egal(double x,double y)
{
	if (isinf(x))
		return isinf(y);
	else return fabs(x-y)<t;
}

int main()
{
	ifstream f("trapez.in");
	ofstream g("trapez.out");
	f >> n;
	for (i=1;i<=n;i++)
		f >> v[i].x >> v[i].y;
	for (i=1;i<=n;i++)
		for (j=i+1;j<=n;j++)
			a[++m]=(v[i].y-v[j].y)/(v[i].x-v[j].x);
	sort(a+1,a+m+1);
	for (i=1;i<=m;i++)
	{
		l=1;j=i;
		while ((++j<=m) && (egal(a[i],a[j])))
			l++;
		i=j-1;
		s+=l*(l-1)/2;
	}
	g << s;
}