#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");
struct punct{long x,y;}a[1002];
int n,i,j,k=1,l;
double b[500000];
long nr;
double panta(punct p1,punct p2)
{
    return (float)(p1.y-p2.y)/(p1.x-p2.x);
}
int main()
{
    f>>n;
    for(i=1;i<=n;i++) f>>a[i].x>>a[i].y;
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
        b[++l]=panta(a[i],a[j]);
    sort(b+1,b+l+1);
    for(i=2;i<=l;i++)
    {
        if(b[i]==b[i-1]) k++;
        else nr+=k*(k-1)/2,k=1;
    }
    g<<nr;
    f.close();g.close();
    return 0;
}