NDT

#include <bits/stdc++.h>
#define task "TESTCODE"
using namespace std;
const int N = 1e3;
int n;
map<pair<int, int>, int > Map;
int x[N + 1], y[N + 1];
void read()
{
    cin >> n;
    for (int i = 1; i <= n; ++ i)
    {
        cin >> x[i] >> y[i];
    }
}
void solve()
{
    for (int i = 1; i <= n; ++ i)
    {
        for (int j = i + 1; j <= n; ++ j)
        {
            if (x[i] != x[j] || y[i] != y[j])
            {
                long long x1 = x[j] - x[i], y1 = y[j] - y[i];
                long long tmp = __gcd(abs(x1), abs(y1));
                x1 /= tmp;
                y1 /= tmp;
                ++Map[{x1, y1}];
            }
        }
    }
    long long ans = 0;
    for (int i = 1; i <= n; ++ i)
    {
        for (int j = i + 1; j <= n; ++ j)
        {
            if (x[i] != x[j] || y[i] != y[j])
            {
                long long x1 = x[j] - x[i], y1 = y[j] - y[i];
                long long tmp = __gcd(abs(x1), abs(y1));
                x1 /= tmp;
                y1 /= tmp;
                ans += Map[{-y1, x1}];
                ans += Map[{y1, -x1}];
            }
        }
    }
    cout << ans/2;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    //freopen(task".INP", "r", stdin);
    //freopen(task".OUT", "w", stdout);
    int t = 1;
    bool typetest = false;
    if (typetest)
    {
        cin >> t;
    }
    for (int _ = 1; _ <= t; ++ _ )
    {
        read();
        solve();
    }
    return 0;
}