#include <fstream>
#include <algorithm>
using namespace std;
ifstream f("trapez.in");
ofstream g("trapez.out");

struct du{
int x;int y;}v[1001];
float n,q[1000001],t,y,s;
int nr,i,j,nrr;
int main()
{
f>>n;
    for(i=1;i<=n;i++)
        f>>v[i].x>>v[i].y;
for(i=1;i<=n;i++)
        for(j=i+1;j<=n;j++){
                if(v[j].x-v[i].x==0)
                    nrr++;
                    else
            q[++nr]=1.0*(v[j].y-v[i].y)/(v[j].x-v[i].x);}
    sort(q+1,q+nr+1);
            t=q[1];y=1;
        for(i=2;i<=nr;i++){
            if(q[i]==t)
                y++;
                else
                {
                    s+=y*(y-1)/2;
                    t=q[i];
                        y=1;
                }}
                g<<s;
                s+=nrr*(nrr-1)/2;
    return 0;
}