#include <iostream>
#include <fstream>
#include <algorithm>

using namespace std;

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

#define lim 1005
#define inf 1000000
int n;
struct pct{int x,y;} v[lim];
long double m[lim*lim],aux;
long long rez=0;


int main()
{
    fin>>n;
    for(int i=1; i<=n; i++)
        fin>>v[i].x>>v[i].y;

    int k=0;
    for(int i=1; i<n; i++)
        for(int j=i+1; j<=n; j++)
        {
            if(v[j].x-v[i].x)
                aux=(long double)((long double)(v[j].y-v[i].y) / (long double)(v[j].x-v[i].x));
            else
                aux=inf;
            m[++k]=aux;
        }

    sort(m+1,m+k+1);
    m[++k]=inf;

    int i=1;
    while(m[i]!=inf)
    {
        int j=i,l=0;
        while(m[j]==m[i])
            j++,l++;
        rez=rez+1LL*l*(l-1)/2;
        i++;
    }
    fout<<rez;

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