#include <fstream>
#include <algorithm>

using namespace std;

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

typedef pair<int, int> Punct;
typedef pair<Punct, Punct> Chestie;

Chestie A[510001];
long double Panta[510001];
Punct P[1001];

bool cmp(Chestie X, Chestie Y)
{
    return 1LL*(X.first.second - X.second.second)*(Y.first.first - Y.second.first) < 1LL*(Y.first.second - Y.second.second) * (X.first.first - X.second.first );
}


int main()
{
    int n;
    fin>>n;
    for(int i=1;i<=n;i++)
        fin>>P[i].first>>P[i].second;
    int k = 0;
    for(int i=1;i<=n;i++)
        for(int j=i+1;j<=n;j++)
        {
            //A[++k] = make_pair(P[i],P[j]);
            if(P[i].first == P[j].first)
               Panta[++k] =  2000000001;
            else Panta[++k] = 1.0*(P[i].second - P[j].second)/(P[i].first - P[j].first);

        }
   // sort(A+1,A+1+k,cmp);
    sort(Panta+1,Panta+1+k);
    //for(int i=1;i<=k;i++)
       // fout<<Panta[i]<<'\n';


    unsigned long long sol = 0;

    for(int i=1;i<=k;i++)
    {

        int d = 1;
        while(
              Panta[i] == Panta[i+d]
                && i+d<=k
              )
                d++;
        d--;
        sol += (d+1)*d/2;

        i = i + d;
    }

    fout<<sol;

    fin.close();
    fout.close();
    return 0;
}