#include<iostream>
#include<cmath>
#include<fstream>
#include<algorithm>
using namespace std;
const double Error=0.001;
struct punct{double x,y;};
punct a[1600];
int n,sol;
int st,dr;
int cmp(punct A, punct B)
{
	if (A.y<B.y)
		return 1;
	if (A.y==B.y)
		if (A.x<B.x)
			return 1;
	return 0;
}
int cauta (punct A)
{
	while (st<=dr)
	{
		int mij;
		mij=(st+dr)/2;
		//if (fabs(a[mij].y-A.y)<=Error)
		///	if (fabs(a[mij].x-A.x)<=Error)
		//		return 1;
			
		if (a[mij].y<A.y-Error)
			st=mij+1;
		else
			if (A.y+Error<a[mij].y)
				dr=mij-1;
			else
				if (a[mij].x<A.x-Error)
					st=mij+1;
				else
					if (a[mij].x>A.x+Error)
						dr=mij-1;
					else
						return 1;
	}
	return 0;
}
int main(void)
{
	fstream f,g;
	f.open("triang.in",ios::in);
	g.open("triang.out",ios::out);
	f>>n;
	int i,j;
	double sin60=sqrt(3+0.0)/2, cos60=0.5;
	for (i=1;i<=n;i++)
		f>>a[i].x>>a[i].y;
	sort(a+1,a+1+n,cmp);
	for (i=1;i<=n-1;i++)
		for (j=i+1;j<=n;j++)
		{
			punct C;
			C.x= a[i].x+cos60*(a[j].x-a[i].x)+sin60*(a[i].y-a[j].y);
			C.y=a[i].y+sin60*(a[j].x-a[i].x)+cos60*(a[j].y-a[i].y);
			st=1;
			dr=n;
			if (cauta(C))
				sol++;
			C.x= a[i].x+cos60*(a[j].x-a[i].x)-sin60*(a[i].y-a[j].y);
			C.y=a[i].y-sin60*(a[j].x-a[i].x)+cos60*(a[j].y-a[i].y);
			st=1;
			dr=n;
			if (cauta(C))
				sol++;
			
		}
	g<<sol/3;
}