#include <iostream>
#include <fstream>
#include <unordered_map>
#include <algorithm>
using namespace std;

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

pair <int, int> p[1001];
unordered_map <pair <int, int>, int> m;

int gcd(int a, int b)
{
    int r;
    while (b)
    {
        r = a%b;
        a = b;
        b = r;
    }
    return a;
}

int main()
{
    int n, i, j, gcdv;
    int rasp = 0;
    map <pair <int, int>, int>::iterator it;

    fin >> n;
    for (i = 1; i<=n; i++)
        fin >>  p[i].first >> p[i].second;
    sort(p+1, p+n+1);

    for (i = 1; i<=n; i++)
        for (j = i+1; j<=n; j++)
        {
            gcdv = gcd(p[j].first - p[i].first, abs(p[j].second - p[i].second));
            ++m[{(p[j].first - p[i].first)/gcdv, (p[j].second - p[i].second)/gcdv}];
        }
    for (it = m.begin(); it != m.end(); it++)
        rasp = rasp + it->second*(it->second-1)/2;
    fout << rasp;
	return 0;
}