#include <fstream.h>
#define inf 100000;

ifstream fin("trapez.in");
ofstream fout("trapez.out");
struct Punct{
	int x;
	int y;
	};
double Panta(Punct A, Punct B);


int main()
{
	int n, i, j, paralele = 0,  k = 0;
	float p[100], aux;
	fin >> n;
	Punct a[100];
	for(i = 1; i <= n; i++)
		fin >> a[i].x >> a[i].y;
	for(i = 1; i < n; i++)
		for(j = i+1; j<= n; j++)
			p[++k] = Panta(a[i],a[j]);
	for(i = 1; i < k; i++)
		for(j = i+1; j<= k; j++)
			if(p[i] >= p[j] )
			{
				aux = p[i];
				p[i] = p[j];
				p[j] = aux;
			}
	for(i = 1; i <= k;i++)
		if(p[i] == p[i+1]) paralele++;
	fout << paralele;
	fin.close();
	fout.close();
	return 0;
}

double Panta(Punct A, Punct B)
{
	if(A.x == B.x) return inf;
	return(float)(B.y-A.y)/(B.x-A.x);
}