#include<fstream>
#include<algorithm>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");

int N,i,j,x[1001],y[1001],k=0,trapez=0,r=0;
float pante[1000001];

void citire()
{
	f>>N;
	for (i=1;i<=N;i++)
		f>>x[i]>>y[i];
}

void panta()
{
	for (i=1;i<=N-1;i++)
		for (j=i+1;j<=N;j++)
			pante[++k]=float(y[j]-y[i])/x[j]-x[i];
}

int gaos(int a)
{
	return a*(a+1)/2-a;
}

void caut()
{
	trapez=0;
	for (i=1;i<=k;i++)
	{
		r=1;
		while (pante[i]==pante[i+1]) {r++;i++;}
		if (r>=2) {trapez+=gaos(r);i--;}
	}
}

int main()
{
	citire();
	panta();
	sort (pante+1,pante+k+1);
	caut();
	g<<trapez;
	return 0;
}