#include <cstdio>
#include <algorithm>

using namespace std;
struct dreapta{
    int x1;
    int y1;
    int x2;
    int y2;
};
dreapta a[1000001];
pair <int,int> v[1001],x;
int cadran (dreapta x){
    if (x.y1<=x.y2)
        return 1;
    return 2;
}
pair <int,int> sin (dreapta x){
    if (x.y1<=x.y2)
        return make_pair( (x.y2-x.y1) * (x.y2-x.y1) , (x.y2-x.y1) * (x.y2-x.y1) + (x.x2-x.x1) * (x.x2-x.x1) );
    return make_pair ( (x.y2-x.y1) * (x.y2-x.y1) , (x.y2-x.y1) * (x.y2-x.y1) + (x.x2-x.x1) * (x.x2-x.x1) );
}
int cmp (dreapta x , dreapta y){
    pair <long long,long long> xx,yy;
    //printf ("%d %d %d %d\n",x.x1,x.y1,x.x2,x.y2);
    //printf ("%d %d %d %d\n",y.x1,y.y1,y.x2,y.y2);
    xx=sin(x);
    yy=sin(y);
    if (cadran(x)!=cadran(y))
        return cadran(x)<cadran(y);
    return (xx.first*yy.second) < (xx.second * yy.first);
}
int same (int i,int j){
    pair <long long,long long> x,y;
    x=sin(a[i]);
    y=sin(a[j]);
    return ((x.first*y.second) == (x.second * y.first) && cadran(a[i])==cadran(a[j]));
}
int main()
{
    FILE *fin=fopen ("trapez.in","r");
    FILE *fout=fopen ("trapez.out","w");
    int n,i,j,m;
    long long sol,l;
    fscanf (fin,"%d",&n);
    for (i=1;i<=n;i++)
        fscanf (fin,"%d%d",&v[i].first,&v[i].second);
    sort (v+1,v+n+1);
    m=0;
    for (i=1;i<=n;i++){
        for (j=i+1;j<=n;j++){
            a[++m].x1=v[i].first;
            a[m].y1=v[i].second;
            a[m].x2=v[j].first;
            a[m].y2=v[j].second;
        }
    }
    // in a am toate segmentele
    // le sortez dupa cadran, si in caz de egalitate, dupa unghiul cu ox
    sort (a+1,a+m+1,cmp);
    //for (i=1;i<=m;i++){
      //  x=sin(a[i]);
        //printf ("%d %d %d %d %d %d\n",a[i].x1,a[i].y1,a[i].x2,a[i].y2,x.first,x.second);
    //}
    l=0;
    sol=0;
    for (i=1;i<=m;i++){
        if (i==1 || same(i,i-1)==0){
            sol=sol+ l*(l-1)/2;
            l=1;
        }
        else if (same (i,i-1))
            l++;
    }
    sol=sol+ l*(l-1)/2;
    fprintf (fout,"%lld",sol);
    return 0;
}