#include <fstream>
#include <algorithm>
#include <iomanip>
#include <iostream>
using namespace std;
ifstream fin("trapez.in");
ofstream fout("trapez.out");
int n;
typedef struct coord {int x,y;} COORD;
COORD a[1010];
double b[500510];
int main()
{
    fin>>n;
    for (int i=1;i<=n;i++)
        fin>>a[i].x>>a[i].y;
    int poz=0;
    for (int i=1;i<=n-1;i++)
        for (int j=i+1;j<=n;j++)
            b[++poz]=(double)(((double)((double)a[i].y-(double)a[j].y))/((double)((double)a[i].x-(double)a[j].x)));
    sort(b+1,b+poz);
    int rr=1;
    int sum=0;
    for (int i=2;i<=poz;i++)
        {
            if (b[i]==b[i-1])
                rr++;
            else
                {
                    sum+=rr*(rr-1)/2;
                    rr=1;
                }
        }
        sum=rr+=rr*(rr-1)/2;
        fout<<sum<<'\n';

    return 0;
}