#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>

using namespace std;

#define inf 3000000000.0
#define NM 1005

int X[NM], Y[NM];

vector <double> pante;

int egale (double n1, double n2)
{
	if (fabs(n1-n2) <= 0.000000001) return 1;
	return 0;
}	

int compara (double n1, double n2)
{
	if (egale(n1, n2)) return 0;
	if (n1 > n2) return 1;
	return -1;
}

int main()
{
	int N;
	
	freopen ("trapez.in", "r", stdin);
	freopen ("trapez.out", "w", stdout);
	
	scanf ("%d", &N);
	
	for (int i = 1; i <= N; ++i) scanf ("%d %d", &X[i], &Y[i]);
	
	for (int i = 1; i <= N; ++i)
		for (int j = i + 1; j <= N; ++j)
		{
			double sus = Y[j] - Y[i];
			double jos = X[j] - X[i];
			
			double m;
			
			if (egale (jos, 0)) m = inf;
			else m = sus/jos;
			
			//printf ("%d %d %lf\n", i, j, m);
			
			pante.push_back(m);
		}	
		
	sort (pante.begin(), pante.end());

	/*
	for (int i = 0; i < pante.size(); ++i) printf ("%lf ", pante[i]);
	printf ("\n");
	*/
	
	int ans = 0;
	
	for (int i = 0; i < pante.size();)
	{
		double m= pante[i];
		
		int j = i;
		
		while (egale(m, pante[j])) ++j;
		
		int cate = j - i;

		ans += (cate * (cate-1))/2;

		i = j;		
	}	
	
	printf ("%d", ans);
	
	return 0;
}