#include <fstream>
#include <vector>
#include <array>
#include <cstdlib>
#include <algorithm>
using namespace std;
struct point{
    int x,y;
};
ifstream in("trapez.in");
ofstream out("trapez.out");
array<point,1005>a;
vector <double>v;
const double eps=1e-14;
const double inf=2000000000;
double panta(point a,point b){
    if(abs(a.x-b.x)<eps)
        return  inf;
    return (1.0*a.y-b.y)/(a.x-b.x);
}
int main()
{
    int n,nr=1,nr2=0;
    in>>n;
    for(int i=1;i<=n;i++)
        in>>a[i].y>>a[i].x;
    for(int i=1;i<=n;i++)
        for(int j=i+1;j<=n;j++)
            v.push_back(panta(a[i],a[j]));
    sort(v.begin(),v.end());
    for(int i=0,x=v.size();i<x-1;i++)
        if(v[i]==v[i+1])
            nr++;
        else
            nr2+=((nr-1)*nr)/2,nr=1;
    nr2+=((nr-1)*nr)/2;
    out<<nr2;
    return 0;
}