#include<fstream>
#include<string.h>
#include<ctype.h>
#include<iostream>
#include<algorithm>
#include<map>
#include<unordered_map>
#include<array>
#include<deque>
#include<math.h>
#include<unordered_set>
#include<set>
#include<iomanip>
#include<bitset>
using namespace std;
vector<double>pante;
vector<double>::iterator it,iter;
int n, i,j,nr,rez;
double m;
int puncte[1010][3];
int main()
{
	//ifstream f("file.in");
	//ofstream g("file.out");
	ifstream f("trapez.in");
	ofstream g("trapez.out");
	f >> n;
	for (i = 1; i <= n; i++)
	{
		f >> puncte[i][1] >> puncte[i][2];
	}
	for (i = 1; i <= n - 1; i++)
		for (j = i + 1; j <= n; j++)
		{
			m = double(puncte[j][2] - puncte[i][2]) / double(puncte[j][1] - puncte[i][1]);
			pante.push_back(m);
		}
	sort(pante.begin(), pante.end());
	nr = rez = 0;
	for (it = pante.begin(); it != pante.end(); it++)
	{
		iter = it;
		iter++;
		if (iter!=pante.end()&&*it != *iter)
		{
			rez += (nr*(nr - 1) / 2);
			nr = 1;
		}
		else
		{
			nr++;
		}
	}
	g << rez;
	return 0;
}