#include <cstdio>
#include <vector>
#include <cmath>
#include <algorithm>

const double INF=(1LL<<31)-1;
const double eps=1.e-14;

using namespace std;

struct POINT
{
    double x, y;
};
vector <double> pan;
POINT a[1010];
inline bool vertical(POINT A, POINT B)
{
    return A.x==B.x;
}
inline void panta(POINT A, POINT B)
{
    if(vertical(A, B))
    {
        pan.push_back(INF);
        return;
    }
    pan.push_back((B.y-A.y)/(B.x-A.x));
}
int main()
{
    int n, i, j, sum=0, nr=0;
    double last, x, y;
    freopen("trapez.in", "r", stdin);
    freopen("trapez.out", "w", stdout);

    scanf("%d", &n);
    for(i=1;i<=n;i++)
    {
        scanf("%lf%lf", &x, &y);
        a[i].x=x;
        a[i].y=y;
    }
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
            panta(a[i], a[j]);
    sort(pan.begin(), pan.end());
    last=pan[0];
    nr=1;
    for(i=1;i<=pan.size()-1;i++)
    {
        if(last==pan[i])
            nr++;
        else
        {
            if(nr>1)
                sum+=(nr*(nr-1)/2);
            nr=1;
            last=pan[i];
        }
    }
    printf("%d\n", sum);

    return 0;
}