#include <iostream>
#include <fstream>
#include <algorithm>
using namespace std;
ifstream f ("trapez.in");
ofstream g ("trapez.out");
struct point
{
    unsigned x,y;
}v[1005];
int n,i,j,k,nr;
struct asd
{
    int m,x;
}p[1000010];
int main()
{
    f>>n;
    k=0;
    for (i=1;i<=n;i++)
        f>>v[i].x>>v[i].y;
    for (i=1;i<n;i++)
        for (j=i+1;j<=n;j++)
        {
            k++;
            p[k].m=v[j].y-v[i].y;
            p[k].x=v[j].x-v[i].x;
        }
    /*for (i=1;i<=k;i++)
        cout<<p[i].m<<' '<<p[i].x<<'\n';
    cout<<'\n';*/
    for (i=1;i<k;i++)
        for (j=i+1;j<=k;j++)
        {
            //cout<<p[i].m*p[j].x<<' '<<p[j].m*p[i].x<<'\n';
            if (p[i].m*p[j].x==p[j].m*p[i].x) nr++;
        }
    /*for (i=1;i<=k;i++)
        cout<<p[i]<<' ';
    cout<<"\n\n";
    sort(p+1,p+k);*/

    /*for (i=1;i<=k;i++)
    {
        cout<<p[i]<<' ';
        j=i+1;
        while (p[i]==p[j])
        {
            nr++;
            j++;
        }
    }*/
    g<<nr;
    return 0;
}