#include<iostream>
#include<fstream>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
struct puncte
{
    int x,y;
};
puncte pct[1001];
double pante[1001];
int main ()
{
    int n;
    fin>>n;
    for (int i=1;i<=n;i++)
    {
        fin>>pct[i].x;
        fin>>pct[i].y;
    }
    for (int i=1;i<n;i++)
    {
        for (int j=i+1;j<=n;j++)
        {
            pante[i]=(double)(((double)((double)pct[i].y-(double)pct[j].y))/((double)((double)pct[i].x-(double)pct[j].x)));
        }
    }
    int ct=0;
    for (int i=1;i<n;i++)
    {
        for (int j=i+1;j<=n;j++)
        {
            if (pante[i]==pante[j])
                ct++;
        }
    }
    fout<<ct;
}