#include <fstream>
#include <algorithm>

using namespace std;

double v[524289];
int a[1025],b[1025];
int n,i,j,k;
long long nr,q;

ifstream fin("trapez.in");
ofstream fout("trapez.out");

int main()
{
    fin>>n;
    for (i=1;i<=n;i++)
    {
        fin>>a[i]>>b[i];
        for (j=1;j<i;j++)
        {
            if (b[i]==b[j]) {q++;continue;}
            v[++k]=(double)(a[i]-a[j])/(b[i]-b[j]);
        }
    }
    sort(v+1,v+k+1);
    for (i=1;i<k;i++)
        for (j=i+1;v[i]==v[j]&&j<=k;j++,nr++);
    nr+=(long long)q*(q-1)/2;
    fout<<nr;
    return 0;
}