#include <fstream>
#include <vector>
#include <algorithm>
#include <cmath>
#define x first
#define y second
using namespace std;

ifstream fin("trapez.in");
ofstream fout("trapez.out");

vector <long double> panta;

typedef pair <int, int> p;

vector <p> v;
int n, paral;

int main()
{
	fin >> n;
	v.resize(n);

	for (int i = 0; i < n; ++i)
	{
		fin >> v[i].x >> v[i].y;
		for (int j = 0; j < i; ++j)
		{
			long double r;
			if (v[i].x != v[j].x)
			{
				long double sus = v[i].y - v[j].y, jos = v[i].x - v[j].x;
				r = sus / jos;
			}
			else r = 1e9;
			panta.push_back(r);
		}
	}

	sort(panta.begin(), panta.end());

	int i = 1;
	long long cnt = ((paral * (paral - 1)) >> 1), crt;
	
	n = panta.size();

	while (i < n)
	{
		crt = 1;
		while (i < n && panta[i] == panta[i - 1])
		{
			++crt;
			++i;
		}
		++i;
		cnt += ((crt * (crt - 1)) >> 1LL);
	}

	fout << cnt << "\n";

	return 0;
}