#include <cstdio>
#include <cmath>
#include <algorithm>
#include <vector>
using namespace std;
struct point
{
    double x,y;
};
vector<point>v;
vector <double>v1;
const double eps=1.e-14;
const double INF=2.e9;
double panta(point a,point b)
{
    if(fabs(a.x-b.x)<eps)return INF;
    return (b.y-a.y)/(b.x-a.x);
}
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n , i,nr1;
    double x, y;
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
        scanf("%lf %lf",&x,&y);
        point nr;
        nr.x=x;
        nr.y=y;
        v.push_back(nr);
    }
    int sum=0;
    vector<point>::iterator it;
    vector<point>::iterator it1;
    point a,b;
    for(it=v.begin();it!=v.end();it++)
    {
        for(it1=it+1;it1!=v.end();it1++)
        {
            a=*it;
            b=*it1;
            v1.push_back(panta(a,b));
        }
    }
    sort(v1.begin(),v1.end());
    int cnt=0;
    sum=0;
    vector<double>::iterator x1;
    vector<double>::iterator y1;
    for(x1=v1.begin();x1!=v1.end();x1++)
    {
        y1=x1;
        double t=(*y1);
        cnt=0;
        while(y1!=v1.end()&&t==(*y1))
        {
            cnt++;
            y1++;
        }
        x1=y1-1;
        sum+=(cnt*(cnt-1))/2;
    }
    printf("%d",sum);
    return 0;
}