#include <iostream>
#include <fstream>
#include <algorithm>
#include <cmath>

using namespace std;

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

const int maxN = 1001,
          maxPante = 1000001;
struct punct {
    int x, y;
};

struct panta {
    long long x, y;
};
punct a[maxN];
panta p[maxPante];
int k = 0, x = 0;

void calcPante(int n) {
    for(int i = 1; i < n; i++)
        for(int j = i+1; j <= n; j++) {
            if(a[i].x == a[j].x) x++;
            else {
                p[++k].x = abs(a[j].x - a[i].x);
                p[k].y = abs(a[j].y - a[i].y);
            }
        }
}

bool panteEgale(const panta &b, const panta &c) {
    if(c.y == 0 || b.y == 0) return false;

    if(b.x * c.y == b.y * c.x) return true;
    else return false;
}

bool comp(const panta &b, const panta &c) {
    if(b.x * c.y < b.y * c.x) return true;
    else return false;
}

long long comb(int n) {
    return 1LL * (n*(n-1))/2;
}

int main()
{
    int n, pEg = 1;
    long long sol = 0;
    in >> n;
    for(int i = 1; i <= n; i++)
        in >> a[i].x >> a[i].y;

    calcPante(n);
    sort(p+1, p+k+1, comp);
    for(int i = 1; i < k; i++) {
        if(panteEgale(p[i], p[i-1]))
            pEg++;
        else {
            if(pEg > 1)
                sol += comb(pEg),
                pEg = 1;
            else pEg = 1;
        }
    }
    if(pEg > 1) sol += comb(pEg);
    if(x > 1) sol += comb(x);
    out << sol;
    return 0;
}