#include <fstream>
//#include <iostream>
#include <algorithm>
#define NMax 1005
#include <vector>
using namespace std;
ifstream in ("trapez.in");
ofstream out ("trapez.out");
struct Punct
{
    double x,y;
}punct[NMax];
double m;
int N;
vector <double> S;
int main()
{
    in>>N;
    for (int i=1;i<=N;i++)
    {
        in>>punct[i].x>>punct[i].y;
    }

    for (int i=1;i<=N-1;i++)
        for (int j=i+1;j<=N;j++)
    {
        m=(double)(punct[i].y - punct[j].y) * 1/ (punct[i].x - punct[j].x);
            S.push_back(m);

    }
    int contor=0;
    sort(S.begin(),S.end());
        int aux=1;
    for (int i=0;i<S.size();i++)
    {
            if (S[i]==S[i-1])
                aux++;
            else contor+=(aux*(aux-1)/2),aux=1;//combinatii de N luate cate 2

    }
    contor+=(aux*(aux-1)/2);
    out<<contor;

    return 0;
}