#include<stdio.h>
#include<vector>
#include<algorithm>
#include<math.h>
#include<set>
#define INF 2000000000
#define eps 0.00000000000001
using namespace std;
vector<double> pante;
pair<int,int> a[1005];
double panta(pair<int,int> a, pair<int,int> b)
{
    if(a.first==b.first) return INF;
    return (double)(b.second-a.second)/(double)(b.first-a.first);
}
int main()
{
    freopen("trapez.in","r",stdin);
    freopen("trapez.out","w",stdout);
    int n,i,j;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
        scanf("%d%d",&a[i].first,&a[i].second);
    for(i=1;i<n;i++)
        for(j=i+1;j<=n;j++)
            pante.push_back(panta(a[i],a[j]));
    sort(pante.begin(),pante.end(),less<double>());
    int l,nr=0;l=1;
    for(i=0;i<(int)pante.size();i++)
        if(fabs(pante[i]-pante[i-1])<eps)
            l++;
        else
        {
            nr=nr+l*(l-1)/2;
            l=1;
        }
    printf("%d\n",nr);
    return 0;
}