#include <fstream>
#include <algorithm>
#define DIM 1010
using namespace std;

ifstream fin ("trapez.in");
ofstream fout ("trapez.out");
long long n,i,k,ap,sol,j;
struct punct {
    long long x;
    long long y;
};
punct v[DIM];

struct segment {
    long long x;
    long long y;
    long long x2;
    long long y2;
};
segment d[DIM*DIM];

int cmp2 (punct a, punct b){
    if (a.x == b.x)
        return a.y < b.y;
    return a.x < b.x;
}

pair<long long,long long> tangenta (segment a){

    pair <long long,long long> val;
    val.first = a.x2 - a.x;
    val.second = a.y2 - a.y;
    if (val.second < 0) val.second = -val.second;

    return make_pair(val.second,val.first);
}
int cadran (segment a){
    if (a.y <= a.y2)
        return 1;
    return 2;
}
int cmp (segment a, segment b){

    pair <long long,long long> nr1,nr2;

    nr1 = tangenta (a);
    nr2 = tangenta (b);

    if (cadran(a) != cadran (b))
        return cadran(a) < cadran (b);
    else
        return nr1.first*nr2.second < nr1.second*nr2.first;
}

int verif (long long i, long long j){

    pair <long long,long long> nr1,nr2;
    nr1 = tangenta (d[i]);
    nr2 = tangenta (d[j]);

    if (nr1.first*nr2.second == nr1.second*nr2.first && cadran(d[i]) == cadran(d[j]))
        return 1;
    return 0;
}
int main (){

    fin>>n;
    for (i=1;i<=n;i++)
        fin>>v[i].x>>v[i].y;

    sort (v+1,v+n+1,cmp2);
    for (i=1;i<n;i++)
        for (j=i+1;j<=n;j++){
            k++;
            d[k].x = v[i].x;
            d[k].y = v[i].y;
            d[k].x2 = v[j].x;
            d[k].y2 = v[j].y;
        }
    /// sortam dupa cadram si in caz de egalitate dupa unghi
    /// retinem tangenta
    sort (d+1,d+k+1,cmp);
    ap = 1;
    for (i=2;i<=k+1;i++){
        if (verif(i,i-1))
            ap++;
        else{
            /// sol += comb ap, 2
            sol += ap*(ap-1)/2;
            ap = 1;
        }
    }
    fout<<sol;

    return 0;
}